FLUX'S EXPERT MAGE GUIDE
Welcome to Flux's expert Mage guide. This is my guide for Diablo techniques for expert Mages to play PvM. I will not be covering duelling, getting started with your new Mage, finding books, gaining EXP, or any of the other low and mid level techniques/tactics. This guide assumes you know something about where to find the good equipment. I will describe, what the common abbreviations used in Diablo mean (e.g. KSOH = King's Sword of Haste) and how to play a basic Mage already. Also note that when I say "expert Mage" that is a bit broader term than "expert Warrior/Rogue".
Why? As your character advances in levels, you gain HPs, mana, and damage points every level up until lvl 50. Rogues and Warriors need more mana, more HPs, and especially more damage, as they rely largely on physical attacks. (Rogues can be very effective in Mini-Mage set ups, but they are still best combining magic with a bow or sword in most situations.) Mages have no use for the added HPs, and the added damage is nice, but as you usually only get 1 point per level up, it is not anywhere near as important as your equipment. The added mana is also nice, but when you have 800 or more already, another 2 or 4 points isn't going to make much difference. So my point is that a Mage at lvl 30 or higher could be considered a high level Mage, and play just about identically to a lvl 50 Mage, providing the equipment and skills were similar, with the only noticeable difference in damage done to stoned full immunes. Whereas a Warrior really needs to hit lvl 45 or so to be able to access the highest skill Warrior tactics and equipment set ups (see Bolty's High Level Warrior Guide for details), and a Rogue needs to get up around lvl 40+.
There aren't many teamwork tips here either. I am writing this mostly for solo play in Multi-Player mode, though you can play identically with another player, providing you each go separate ways in the dungeon. Mages only get a benefit by teaming up on the full immune levels anyway, most of the time. One major point in the 'how to play an expert Mage' debate is the “Artillery” vs. “Battle-Mage” debate. I will not go into a detailed comparison in this guide. Instead my personal preference or recommendation will be detailed here, which is roughly a hybrid of the two styles. Basically using “Artillery techniques” wherever they are more appropriate and quickest, while wearing “Battle-Mage equipment” when needed.
I do not advocate frequent equipment switches, so I will not be putting in perfect equipment for various monster combinations. Generally speaking, the time you would save doing a given level with the absolute perfect equipment, would not be enough faster to make up for the time it would take you to pop back to town and change gear, nor to offset the loss in blue carrying capacity if you were hauling around more spare items than a weapon and perhaps one or two alternate jewels. More fundamentally, this is a guide to a playing style that can be used at least 90% of the time w/o any equipment changes or major strategy alterations.
Possible future revisions to this guide will add more details if they seem pressing, but I will make every effort to make this a good, useful “Expert Mage Guide” w/o going into the details that an absolutely “Complete Mage Guide” would cover. With this you should be able to transform yourself from a sloppy lvl 35 Mage who needs to hit town every level in hell/hell for more blues, to a precise and deadly assassins who can clear 13-15 and at least part of lvl 16 before running dry on blue, and in no more than about 5-10 minutes per level. (Closer to 5 than 10 would be better.) Runs of 13-15 hell/hell in under 20 minutes are not at all out of the question if you don't get just awful luck on the monster draw. Lvl 16 itself, especially on hell/hell, can take even an expert Mage as long as the 3 other levels of hell put together, with the fully immune advocates and HP rich blood knights slowing everything down a lot. But fear not, I have plenty of strategies for all of these levels in this guide.
Discussion of +spell level items
One thing affecting most of the equipment choices in this is the Battle- vs. Artillery-Mage argument. I mentioned already where I come down in it, but let me make a quick comment on the +spell level items, so I don't have to go over it again every time I discuss DF, TC, AA staff, Naj's Plate, etc. Also, let me add that +spell levels is not all Artillery-Mages are about, as there is a whole different playing style involved, (by necessity, as you can't let anything close enough to hit you or it's going to hurt.) and in addition to higher spell levels more mana is much sought after. However, as the biggest trade offs in equipment choices mostly involve +spell level items, I'm mentioning it here. Adding to your spell levels can seem very tempting for a Mage. You will of course have everything useful to lvl 15 by this time, but looking at how much your Fireball's damage is increased but boosting it to lvl 16 or 18 or the (legit) max of lvl 20 can be thrilling. However, let's consider some spells and how they are effected under +4 or +5 spell levels.
Commonly used spells
What, if anything, changes when these spells go up in levels?
Chain Lightning - No real benefit, possibly detrimental. Many Mages intentionally keep theirs down around lvl 10 or 11 so as not to send out so many bolts and reach the sprite limit that much more quickly. (I've never subscribed to this, believing it's better to have all the levels of chain you can get, and to learn to control it better though positioning and tactics.) Certainly if you are keeping it down at 11 by not reading more books you don't want to pop it up to 15 or 16 due to your +spell level equipment.
Fireball - Big advantage. The higher the level, the faster it travels and the more damage it does.
Teleport - No effect.
Stone Curse - No effect.
Golem - Small benefit.
Mana Shield - No effect.
Occasionally used spells
Town Portal - No effect.
Guardian - Improved slightly.
Flame Wave - Improved slightly.
Charged Bolt - Improved slightly.
Elemental - Improved somewhat. Of course the listed damage skyrockets, identical to Fireball damage, but since this spell does not calculate splash damage erroneously (Fireball doubles splash damage) as Fireball does, it will do much less than the listed damage, which is why Elemental is an "occasionally used spell" and Fireball isn't.
If you want to go Artillery style and +spell levels, you are basically doing it for more damage with your Fireball, at the slight expense of your Chain Lightning, and adding slightly to a bunch of spells you hardly ever cast anyway. One must weigh the trade-offs of each item of +spell level individually, as compared to your other options, and that will be done later, in the equipment run down.
Discussion of +attributes
Strength - Raising your STR increases your Mage's damage, and also you need at least 90 STR to wear plate mail, the best (and most highly recommended) body armor. You only get 45 base, so several items are required to get a Mage's STR up to any sort of a decent level.
Dexterity - Raising your DEX increases your AC, and also increases your success in blocking an attack. This is not a very useful attribute for a Mage, as your goal is to kill things before they get close enough to have a change at hitting you in the first place.
Magic - The most important stat for a Mage, and yet not all that essential to raise. You get 250 base, which equates to 500 mana at a minimum, not even including the +2 mana you get per level up. You need 255 to read the highest level of books, but most expert Mages will have up around 300 magic with any sort of decent equipment, and usually some +mana also, from Dragons/Drakes type of items, or especially from the Royal Circlet.
Vitality - Virtually worthless. Mages use Mana Shield constantly, and as Mages only get 1 HP per vitality point, and aren't using their HP's anyway, don't worry about this. It's not uncommon for lvl 38 or even 40 Mages to still not have their vitality stat maxed out, and to pass by vitality elixirs without a glance. However as Zodiac jewelry, along with some other useful +to all attribute items do hit vitality also, you might as well accept getting some bonus to this attribute, like it or not. One other place you may get stuck with some +hit points is from your shield, as there are very few decent suffixes allowed on shields, especially in conjunction with the desired prefixes. See the shield section for more details. A goodly amount of hit points can occasionally be useful. For example if you are careless and get hit hard enough to drop your Mana Shield, having 150 or 200 vitality can keep you alive long enough to teleport to safety and re-engage Mana Shield.
Advantages - Good AC (40), +10 to all helps on damage and mana and STR for wearing armor, +40 mana rules also.
Disadvantages - None really. Some dislike the +10% light radius, but I never minded that. Spells are flying so much that plenty of off screen monsters are always coming in anyway, and I don't mind seeing things further away from me. Gives a Mage more time to decide which spell to use on them, and to get as many hits as possible in before they can close to melee range.
Advantages - Huge AC (60), +20 to all is very nice, easier to find than RC (debatable).
Disadvantages - -40% light is a bad thing. If I need to put 6 or 7 chains into those Steel Lords, better I see them before they are 5 squares away. 0% resistance to all is a disaster also, making this only usable on melee levels. As a Mage you are going to be taking by far the most damage from ranged attacks, mainly Bood Stars and Fireballs, so resistance is more important than AC. Also 20 less mana than RC.
Advantages - +2 spell levels, +30 mana
Disadvantages - awful AC (1-4) unusable durability (1/1, at least initially).
Awesome great helm of stars/sorcery
Mages get a bit screwed here, as neither sorcery nor stars can be suffixed on "godly" or "holy" helms. Pros to these "awesome" helms are; up to 45 AC and +11 to all or +20 to magic, but they are still pale imitations of the mighty RC.
Obsidian great helm of stars/sorcery
This can be useful, but only if you can't find an RC, TC, or are truly desperate for resistance. I'd recommend the obsidian/stars for all around utility, with obsidian/sorcery only netting you 18 more mana than the stars, at the cost of everything else.
I'd recommend RC for 95% of the situations you'll find yourself in, only switching to TC in no-melee levels, for example Witches and Advocates, or for normal/hell item runs, or possibly for nightmare/hell lvl 16, where you need the extra Fireball damage for the fire resisting Blood Knights and Advocates, and +2 spell levels might save you a Fireball per monster. Just be extra careful (Artillery-Mage style) not to let get any knights close to you, as the loss in AC will get you hit most of the time, and just one hit every five or ten knights will negate all of the mana an time you were saving by having to shoot fewer Fireballs at them.
Naj's Light Plate
Advantages - +1 spell levels. Not much STR+ required to wear it.
Disadvantages - Awful AC, only +5 magic, small resistances bonus.
In the trade-off between +spell levels and the disadvantages associated with them, this is maybe the least attractive of the +level items. Purely for no-melee levels, as anywhere else the lack of AC will get you killed, or force you to play so carefully to stay out of range or melee monsters that the benefit of the +spell level is gone.
Awesome Full Plate of sorcery
Advantages - Best AC you are going to get, +20 magic.
Disadvantages - Requires 90 STR to equip, very hard to find.
Awesome Full Plate of the stars
Advantages – Excellent AC again, +11 to all helps everywhere.
Disadvantages - Very hard to find.
Awesome Full Plate of the giants
Advantages - AC, +20 STR covers a lot of the ground from 45 to 90. Nice bonus to damage also.
Disadvantages - No magic/mana+. Not a very wizardly-sounding item.
Awesome Full Plate of anything else
Advantages - AC of course.
Disadvantages - It's not sorcery or stars or giants.
In summary, whatever Awesome Plate you can find/buy with the highest AC is your best bet here, almost always. Trade-offs come in when you have something like Saintly/Stars and find a plain Awesome plate. You would need to weigh the +AC with the loss in other attributes, and that depends a lot on your other equipment.
Though it seems counter-intuitive, since +STR is fairly useless to a Sorcerer, "of the giants" might be the best option. Why? Compare it to the other available mods. Body armor can’t spawn with heavens or zodiac or wizardry, so by using giants as the suffix on your armor you are not giving up a great alternative as you would be with giants (or titans) on a jewel. And since you need to add +45 strength somehow, to reach 90 SR for FPM, if you can get 20 of it from your armor that's enough to let you wear the FPM with just a couple of heavens jewels, which might free your other suffixes for wizardry.
Advantages - +1 spell levels, +30 magic, +50 mana, +light radius +50 magic resistance
Disadvantages - Weak damage, can be hard to find.
Advantages - +200% Damage vs. Demons (huge damage)
Disadvantages - -2 to Magic -5 to Dexterity (114 less mana than DF offers) doesn't work on non-demons.
King's Bastard Sword of haste/speed
Advantages - Fastest attack, good damage, good +to/hit
Disadvantages - no magic bonus, no resistance bonus, less damage than the CC where you are using it.
Merciless/Ruthless Bastard Sword of haste/speed
Advantages - Same or nearly the same damage as a KSOH, but cheaper to buy and repair.
Disadvantages - Missing the to/hit bonus, but since your targets are all stone, that's not a big deal.
Arch-Angel's Staff of Apocalypse
Advantages - +2 spell levels, around 10 charges of apocalypse.
Disadvantages - No +magic/mana, no shield = -AC, no blocking, crappy damage for melee.
Arch-Angel's Staff of wizardry
Advantages - +2 spell levels, +30 magic.
Disadvantages - Same as AAA, but at least you do get some magic added.
Over all DF is the way to go most of the time. You'll need the AC from your shield, you get the biggest mana bonus of any weapon, and +1 spell level is not bad either. The only times I'd consider switching are on lvl 15 hell/hell if you get Soul Burners, and then for Lazarus' room and lvl 16. The reason of course is that you are going to be dealing with fully immune monsters, and whacking at them with DF is not a real sound strategy, being as we're playing for speed and precision, remember? Of course use your Golem liberally (much more strategy below) but even with his help, if your damage is around 55 or 60, you can count the number of hits it will take you to kill 70-110 Soul Burners or Advocates per level. And no speed or haste on that DF either.
It would seem that a KSOH is your best bet at this point, but for the lesser known CC. The Civerb's Cudgel is a lowly mace, with only the 1-8 listed damage, but that +200% damage to demons (In dlvl 13 - 16, only lava maws are not classified as demons. They are animals.) applies to your overall damage, not just the 1-8 for the mace. Figure that your overall damage is around 65 or 70 with it equipped, and you can see that you are suddenly going to be doing 200, or good Warrior damage. Of course your swing rate will be far slower than a Warrior, and you have no to/hit bonus with the CC, but since everything you are hitting will be stoned or a barrel anyway, who needs +to/hit? (Not to mention the AC bug helping you out there.)
It's also not a bad idea to carry a Dreamflange and maybe a Thinking Cap along with your equipped RC and CC down to lvl 16, hell/hell. Walk or teleport into new areas, luring as many of the Blood Knights as possible after you around the corner. Then get set where the Advocates aren't shooting you, (line up next to a wall for best accuracy and monster grouping) and lvl 18 Fireball like a fiend. Once all or most of the knights have been lured out of an area, it's much easier to switch to your best melee weapon and teleport back in and set to bashing the statues. Your Golem will last much longer without knights around also.
Advantages - Good AC (40), fast block, +10 STR, Indestructible, easy to find.
Disadvantages - +4 damage, no bonus to magic/mana.
Godly tower shield (of the ages)
Advantages - huge AC, up to (60), ages = indestructible
Disadvantages - No bonus to any stats, no suffix possible besides ages.
Emerald/Obsidian of absorption/ages
Advantages - Very nice resistance, avoid some damage or repairs.
Disadvantages - No more than 20 AC can be a problem.
Awesome of absorption/ages
Advantages - Decent AC, up to 50, and avoid some damage or repairs.
Disadvantages - Not the most AC you can get, pretty lame suffixes.
Shields are rather a pain in terms of what is available. There is a very limited number of useful suffixes possible on them. The basic game limit is of the moon, power, brilliance, etc. Far from the best suffixes, and due to the item creation limits (more info on this and everything else in Jarulf's Guide.) you can't even get those with any of the good prefixes. For example it is impossible to generate an emerald/obsidian/awesome/godly/holy shield of the moon. The suffix "of the moon" has too low an ilvl to be found on the same item with any of those nice prefixes, and since stars, heavens, sorcery, etc are not allowed on shields, you don't have too many choices left. Unfortunately for Mages, the best suffixes possible on shields are wolf and tiger, neither of which are of any real use. Still, better an emerald-obsidian/tiger shield than a plain emerald. It might save your life someday with those extra 40-49 hps.
My recommendation for shields is mixed. The AC is a real help, and getting a nice obsidian or emerald one can be great, as it frees up one of your jewelry prefixes for some +mana, but I'm always sort of frustrated by the lack of any really nice ones for Mages. I'd recommend either godly for the most ac, or emerald/obsidian for the resistance. Stormshield is a popular choice, but the only thing I really like about it is the shiny gold print, and +10 STR. The AC is nice, but can be far outdone by a good godly shield. The fast block is helpful at times, but let me explain something. Fast block doesn't mean you block faster/better. It means that after you block (your success in blocking is largely determined by your dexterity), you recover more quickly to become ready to block or do some other action. This is nice in that you can block and then go back on the attack by casting a spell more quickly, but most people think of SS as nice in that you can block several times rapidly. Well that's fine for a Warrior (of course they have fast block as a class specific skill already though) or a Rogue in melee, but as a Mage, you aren't supposed to be getting hit more than once anyway. Check the tactics section coming up next for more on this, but if you are getting surrounded and beat on by mobs with any sort of regularity, you really need to change your tactics, not just your shield.
As with everything, you can't use it if you haven't found it. And godly shields don't grow on trees, except for Wirt-trees. He is the only place you can get a godly or holy shield. Stormshield is a slightly buggy item in terms of its generation, as it is the only unique gothic shield, and also the only unique tower shield. Both use the non-unique gothic shield animation however. So it is found pretty often, as it is 2x the likelihood right there, being both a tower and gothic shield, and also its ilvl is right in line with most of the mlvl's you encounter in hell. I'd say that SS is the unique I've found the most often in hell, especially in Laz's room with the 3 unique bosses there. And since hell is where expert Mages like to play, you are pretty likely to come across one yourself.
Advantages - instant max resistance to everything.
Disadvantages - lose points from Mana Shield constantly.
Basically you should be getting your resistance from elsewhere by now, but this might not be such a bad item to carry for recover runs after death. The slow drain of mana isn't a big deal when you have 500 or more.
Obsidian of the zodiac
Advantages - Superb resistance and +20 to all is tremendous.
Disadvantages - Good luck finding one.
Dragons or Drakes or Serpents of the zodiac
Advantages - Great +mana and +20 to all.
Disadvantages - Again, very tough to find.
Obsidian or Dragons of wizardry
Advantages - Great resistance or mana with +30 to magic, easier to find than ob/zod or dragon/zod.
Disadvantages - Mage has tons of magic already.
Dragons or Obsidian of titans
Advantages - The great resistance/+mana, and huge (30) +STR if you need the STR.
Disadvantages - Shame to waste a suffix for just more STR. If you really need +30 STR, I'd say take a zodiac and a stars over a titans any day.
So many options on jewelry. All of the above listed are very difficult to find, with obsidian/zodiac items probably being the hardest to find yet most sought after items in the game, which takes any discussion of them into the realm of "dream setups". However, drakes/heavens or obsidian/wizardry aren't unreasonable goals at all. If you are more into the Artillery-Mage goal, dragon/wizardry is for you, as maximizing your magic/mana is the biggest goal. However unless you have an obsidian helm and shield, (and as RC is the best helm, that is NOT recommended) you are likely going to need to use at least one jewel for resistance. Something like drakes/zodiac, obsidian/ wizardry, and dragon/ wizardry is a very nice set up, though you might want to throw in another zodiac item for levels where you are having to bash fully immune things. Just one zodiac item can add 5 or 6 to your damage, and if you consider that you will be swinging 20+ times at 80 or 100 monsters per level, (minus what your Golem does for you) that's a very large difference. Plus the zodiac will raise your AC and to/hit a few points, and if you are using one all the time it takes you a long way towards the 90 STR you need for your armor.
Assumes all base AC and prefixes/suffixes are as close to perfect as possible.
Royal Circlet (Switch to Thinking Cap for all-Fireball levels)
Awesome Full Plate Mail of the giants
Dreamflange (Switch to Civerb's Cudgel for full immunes)
Emerald Tower Shield of the tiger
Obsidian Jewel of the zodiac
Dragons Jewel of wizardry (2)
Armor of the giants is recommended here in the dream setup as it gets you +20 STR (with the goal being at least +45), freeing up a space to change one of the jewels from zodiac to wizardry, which nets you more magic/mana than you would get with a zodiac ring and sorcery on your plate mail. You would need to switch from one of your dragon/wizardry rings when equipping the TC here, as your STR would drop too low to equip the armor. The tiger suffix to the shield is debatable, but as your only other options on an emerald shield are "of the ages" or "of absorption" I'd say take tiger for the "just in case" value. This is also for Mages lvl 40+ as it will not provide enough AC (see the max AC needed chart) for maximum efficiency for clvls 30-40, generally speaking.
What to hotkey?
For levels 13 -15 (not including Laz's room), I never vary from Fireball, Chain Lightning, Stone Curse, and Teleport. Very occasionally if I'm on a no fire or no lightning monster level, I'll switch and throw in a Guardian or Flame Wave or Charged Bolt or Bone Spirit, but usually if the level doesn't require any Chain Lightning, for example, I'll just use only Fireball and not even pause to alter my hot keys.
Once I reach Laz's room and then for lvl 16, (since there are advocates in with Laz, it's unofficially the start of lvl 16.) I switch Chain Lightning for Golem. Golem is very mana-expensive, but it is indispensable for dealing with triple immunes. It's great for Advocates, and still useful for Soul Burners, but must be used more judiciously, as any type of Witch will target a Golem from any distance, and unless you have him virtually in a corner, he's going to be Bloodstar bait and then gravel in just a few seconds.
Recommendation is to still use him a lot on lvl 15 if you get Soul Burners, but just try to make sure you have all the live Witches in the area on stone before you pop him out, or he's not going to last long enough to help much. Soul Burners are probably not as bad as Advocates, due to the much lower damage of their Bloodstars compared to the Advocates Fireballs, and their less unpredictable escape patterns, but they have many more HPs, so a Golem's help in killing them is really a must if you don't want to spend an hour on lvl 15. The one nicer thing about Soul Burners is also one thing that makes them tougher. Namely that they will follow you around corners. It's nice to lure a few away from a room crowded with other monsters, but if you get into trouble and need to bail out to reload your belt or recast Mana Shield, you will have to teleport a bit father way to shake the pursuit of the Soul Burners.
The biggest thing is of course cast Mana Shield the instant you enter a new level. Witches require very different tactics than melee monsters or Mages, for example. It is essential that you know how a monster will move, what it will be hurt by, and what it will hurt you with. That being said, for your attacks Fireball is generally more accurate, precise, and deadly than Chain Lightning, or any other spell. Fireball does a lot more damage, in almost all situations, and you can be standing anywhere and fire it at will. (No worries about proper positioning like with Chain Lightning. More on that later.) If a monster resists both fire and lightning, use Fireball almost all the time on it for the superior accuracy, and use Fireball liberally. Misses may hit the monster next to or behind it, and splash damage is your friend. The liberal use goes for every spell, (except Chain Lightning in certain situations.) most of the time, not just for Fireball. The damage you take (and therefore the mana you lose) from being hit by anything in hell/hell is almost certainly going to be much higher than the mana you would have spent to kill the offending monster if you had cast a little more quickly.
Some screenshots with information about Succubi behavior.
Witches are easily confused by proper positioning. Of the ten Succubus visible, only one, the one on the lower left, is hitting me. The others are hitting the wall. When playing for speed and precision, it's often better to let monsters clump up before attacking, since spells hit more enemies per cast when the enemies are in close proximity. This is especially true of Chain Lightning, with which these Witches will soon be destroyed.
A few casts of Chain Lightning were sufficient to finish the Succubi. Though this position was excellent for avoiding the incoming Bloodstars, it's sub-optimal for Chain Lightning, since so many streams were drawn to the left, towards monsters on the other side of a wall.
Soul Burners are the smartest type of Witch and will walk around corners to get clear firing lines, while other Witches stop short and shoot the wall. This is something of more importance to Rogues, since Soul Burners are triple immune on Hell, but it's handy knowledge to use on Normal or Nightmare.
It is perhaps your most useful, and also most easily misused spell. Positioning is everything.
You should almost never cast chain unless you have a wall on at least one side of you. You also have to take into consideration the sprite limit, and not plan on chain being too effective in big open rooms with tons of targets. Use it intelligently. The sprite limit effects chain even if it's well off the screen. You shoot out a huge burst, it flies through the monsters it was targeting and continues off the screen, where you can hear it moving in the distance. So you click chain again, and get like 3 streams instead of 20. Normally most of your chains will hit a wall before they even get off screen, but occasionally you must wait a moment to get another massive burst, rather than clicking frantically to get a lot of little dribbles.
Chain Lightning works best when you can get the monsters where you want them. Back up a few steps or around a corner to lead them in. Lining monsters up works especially well with Witches, as they'll follow you around a corner and stay in a line, politely holding still (while shooting Bloodstars at you) while you irradiate them with chain or Fireballs.
Other useful features of chain are that you can see how many critters are close to the other side of a wall by how many bolts target them with a test shot. You can be in a 2 or 3 space wide corridor, and find that there are a million targets on the other side of the wall to your right. Therefore if you are shooting chain at things ahead of you, stay touching the right wall. (The left wall is either an outer wall of the level or leads to an already cleared area.) Then when some of the monsters from in front of you come in close, especially if they like to mince around, like Balrogs, you can pop or walk to the other side of the corridor, putting them between you and the populated room to the right. Chain them now and they'll get in the way of all the shots heading towards that wall, and they are toast. This is one way that chain can do the most damage in the game, as you can kill off hell/hell Steel Lords and other lightning resistant monsters with loads of HP in just one or two shots if you have them at the correct angle with a nice background.
It can also be fun to know your targets are lightning weak, and pop over a wall into a big room, land right in the corner, and start chaining away. If you begin hitting the chain (this works with Fireball as well) as soon as you are in mid-teleport, it will issue forth from you the instant you land, before even the monsters' instant reactions can start to hurt you. This is a somewhat risky technique however, because of the next topic.
Stun-lock can be a big problem for Mages. Beware dogs, Azure Drakes, and lightning bugs. (All type of the hidden monsters have high to/hit and rapid swing rates also, so beware them, but any high level Mage should have a high enough AC to not have too much trouble with them.) Getting more than 2 or 3 of them up close is a very bad thing.
You can suffer a curious fate, as you will be trapped and unable to move or cast any spells, but not taking so much damage that you die instantly. It's often not a problem to drink potions from your belt faster than you are taking damage, but drinking from the belt does not equal escaping them. Stay cool. Often it will be impossible to teleport out or blast them with lightning or fire, but you will be able to walk away, and teleport to safety the instant you are able to.
If walking out isn't possible, try use non-targeting spells. Spells that do not have a target are .05 seconds faster to cast, so Phasing might let you escape when Teleport will not. Another decent escape trick if you can't get off a spell is to wait a second or two, (drinking blue madly in the meantime) and then try to cast it again. The monsters hitting you often get a rhythm of sorts going, and if you pause an instant and then try again, you might get off of their pattern and sneak in one spell.
If you are playing with another player this is a very good time to try out those F5-F8 keys.
The best way to avoid stun lock? Don't get surrounded, of course. At least not by melee monsters with fast attacks. Knights don't strike as quickly as these lesser monsters, but they generally have a better to/hit, and they tend to hit harder and have more hit points to take more damage before they stop hitting. You are a Mage, getting closer than 2 or 3 squares from anything that can swing at you is never a good idea.
Mixed resistance levels
If there are two or three monster types on the level with mixed resistances, you have some options. If you have a lightning bait/fireproof monster (lightning or fire bait = no resistance to that spell) and a lightning resistant/fire bait monster, go with mostly lightning, as it will kill one off and wound or kill the other. Though Fireballs would be nearly as effective for the lightning bait/fire resistant monster, they'd have no effect on the lightning bait type. Of course if you come upon a pack of the fire bait type, switch instantly and incinerate them. And of course work on killing the more deadly monsters first. If you have Balrogs and Blood Knights, better you fireball the Knights first, shooting right through the fireproof Balrogs as they mince around breathing their worthless Infernos at you. Of course if there are 9 Balrog's in your face and 1 knight off to the side, a few chains are in order.
Walk to encounter new monsters, but once sighted teleport to get into position if it's more than a square or two away. Walking backwards to get a little space between you and a pack of advancing melee monsters is very inefficient. Teleport half a screen away, and let the Fireballs or Chain Lightning rip. Another problem with walking is the tile-based floor sets in Diablo. Your Mage must be all the way to the next tile before he can cast any spells. If you have a flock of Fireballs or Steel Lords closing in on you, teleport rather than trying to take one step and then teleporting. It doesn't take very long to move from one tile square to the next, but it can seem a very long time if you are clicking frantically trying to teleport or start squeezing off the Fireballs. A Mage casts spells at the rate of one per every .4 seconds. (Not quite fast enough to stun lock, as that requires .35 or faster, though some things are stunned by spells, so you can lock them up if you do enough damage.) All characters walk at the rate of 1 square per .4 seconds, so you can cast a spell in the same time it takes you to walk one space.
However, walking is still used a lot of the time. When exploring a section of the dungeon, unless you know for sure that the monsters on that level aren't very tough, it's never a good idea to just pop over unknown walls. This is by far the fastest way, and if you have an easy level by all means go ahead, but it will take you a lot longer to restart in town and go down to retrieve your equipment than it would have to exercise a little more caution. Advance by walking a square or two at a time, again depending on the monsters you are dealing with. On most chain levels it's best to walk into the middle of the room, then walk or teleport back to your best firing position, leading in a horde of beasties and cooking them as they follow you around the corner. This can be good for Fireballs also, either to avoid getting swarmed or just to increase your efficiency. The nice thing about having decent AC (ie not playing Artillery-Mage style) is that you don't need to be as cautious all the time, and if you have Cave Vipers or some lesser melee beast hitting you now and then, it's not a big deal.
Positioning is also important. Very important for Chain Lightning, but also for Fireballs. Better you retreat with a Teleport than get hit. For example on lvl 16, you will take well over 100 damage from a hit by a Blood Knight. For the same or less mana expenditure, and in about the same amount of time, you could have teleported back, stoned it, and hit it with 4 Fireballs. Or teleported and fired off 7 or 8 Fireballs, killing several knights. Get the idea?
Telekill isn't just for Warriors. Do not walk, do not stay in the same place. This is less important against melee monsters than Advocates or Witches, but pop all over the place every chance you get. Teleport, fire off few Fireballs (with good aim, of course) or stones from one spot, then teleport elsewhere quickly. The monsters are never surprised. You teleport in over a wall behind them, they don't stop to think or try to figure where you came from. They instantly begin shooting at you. But as you can shoot a couple of Fireballs and teleport before their slower projectiles reach you, it's a good idea to do so. Telekilling also works well the Warrior way, popping in close to the various types of Mages or Witches so they will begin to flash you or run/teleport themselves. Either choice is better than absorbing Fireballs or Bloodstars.
On stoning, it costs you 40 mana, and again, anything that hits you in hell/hell will do a lot more than that. (With the occasional exception of Bloodstars and some of the weaker lightning based attacks. Or if you have a bunch of osmosis or deflection items and a Scavenger's Carapace, but I'm not getting into every last little wrinkle here. Especially melee monsters, if they are coming too quickly for you to kill them off (as frequently happens with Azure Drakes and Steel Lords) it's a good idea to stone the ones in the front of the pack to give yourself a few more seconds.
Stone Curse is also highly recommended for Advocates on lvl 16. A Mage can stone very quickly, and once you hit them, monsters stay stoned for quite a while. Up to 16 seconds, depending on the level of your Stone Curse. Plenty of time for you to reload your belt, or escape, or move in and crush them. Stone also works over walls, sight unseen. (Though this could be considered a bit cheesy, in the bountiful apocalypse staff way.) Send in your Golem and see where the Advocates start flashing, and stone them before they can teleport away from the Golem. You'll know you got them if the flashing stops. If you know what monsters are in an area, feel free to stone about 10 times, and then teleport in and pick them off. Stone does not cost you any mana if you miss, and you can't stone something that was already stoned, so target an area, click it a few times, and then feel pretty secure about teleporting in. Of course if you have infravision working that's even more accurate, though it is even cheesier. Though cheesy is in the eye of the beholder.
Also remember that your spells have no max range. Sounding out a long hallway (there are a lot of them in hell) with a few Fireballs or Elementals or a Flame Wave is never a bad idea. Charged Bolt is also very useful for getting lightning bait monsters to come out and play. Guardian can be used for this also, but as it's very mana-expensive (30 per Guardian) use it sparingly. (The duration of a Guardian is based on the level of your Guardian spell. The damage they do is based on the level of your Firebolt spell. Obviously raising both of those is essential for maximum effectiveness.) Also, Guardians are stupid and don't know from fire immune/resistant. You can easily cast 3 Guardians into an unexplored room, and all 3 would shoot 20 shots at the one fireproof monster in the room, doing you absolutely no good unless they happened to hit a fire bait monster behind the fireproof one they were shooting at. Very seldom can you not do more good with 3 Fireballs than 1 Guardian, if you play properly.
Chain can work too, but it won't target monsters more than 15 or so spaces away, (the targeting range increases with your spell level, along with the number of things that can be targeted) so it's less useful for getting them to come and play. It can also be too good at attracting attention, often shooting off in directions you had no intention for it to go, and bringing in hordes of beasties you are not in a good position to battle. Be very careful using chain while you are still near the entrance stairs, as 20 Balrog's mincing all over the place can be a very bad thing when you have nowhere yet cleared to retreat to.
Of course always cast a Town Portal at least a screen away from the stairs 2nd thing on a new level. 1st thing is always hitting up the Mana Shield. Remember about chain always, it knows no walls.
A quick last note on Golems, since I only briefly mentioned them before. They are controllable, going in the direction you are facing, and they are pretty resistant to monster spells, or at least flash. They don't fare so well being on the wrong end of your spells though, so aim carefully, and of course you can't stone them, so give them cover of stone, especially against knights, and stone the advocate they are whacking on, so it can't teleport away, and also so it will stop flashing your Golem. Flash does do some damage to your Golem, just not very much. Be careful to change your hotkey off of Golem as soon as you cast one, as it is easy to forget and try to shoot a Fireball and cast another Golem, and you just blew 180 mana. (Sixty for the one you just killed, 60 for trying to cast another when the first was still out and killing it, and 60 for the one you now have to recast to replace the 1st.)
This should be a major and very important section, but sadly enough, it's not. Why? Because Diablo isn't anywhere near as difficult as he should be. This is a quick reference table; his full stats can be seen here.
A Mage in battle setup can pretty easily defeat Diablo just by standing and swinging with a shield, (a shield is actually faster for a Mage to swing with than a non-haste/speed weapon).
The apocalypse Diablo attacks with is nasty only if you are moving or w/o a shield, as you can almost always block it if you remain stationary. Ways to speed up his death are adding spells that will keep on giving while you are taking the brunt of his affections. Golem, Firewalls under Diablo's feet, or many Guardians all work nicely. You can also cast a bunch of Firewalls and/or Guardians in an area and then teleport over the wall or even die. Your Guardians or Firewalls will live on and keep hurting him, and he's too stupid to run.
But these are the finesse techniques. I used to just take him face to face and treat him like a big Blood Knight, IE Fireball, Fireball, Fireball, repeat as needed. If you lack the AC to let him get close and keep casting spells, you can leapfrog him with teleports and always have him advancing on you. It might be more difficult to hit him then however, as he has a bit of the happy feet and will prance around some in the fashion of a Goat man or a Balrog. (Diablo has the same AI as Magma Demons.) He also has a knockback attack, so it's important that you choose your place of battle carefully, with your back to a wall and your Firewall right in front of you, so he doesn't come in and knock you back and then advance a step, moving right out of the Firewall. From the chart you can see that Diablo is vulnerable to lightning as well as fire, but Fireballs do so much more damage that they are the way to go, even if you get a very nice background for the chain. I've killed Diablo on normal and nightmare by luring him out of his box with Holy Bolt, moving over to the side so I had a nice corner shot at his box, and then chaining him with fifteen or more streams going out aimed at the Blood Knights and Advocates in his box and hitting him on the way. Holy Bolt can also be very useful for killing him on normal, as you should be able to stun lock him with it.
One other tip, if you keep a space clear in your inventory, it's not that hard to grab whatever Diablo drops. Get him almost dead, and have him in a fire field or with sufficient Guardians, or else have him attacking you while your Golem hits him from behind. Then cast Telekinesis, so you get the TK cursor up, but don't click it on anything yet. Wait for Diablo to die while you have the TK cursor ready, and you'll have about 5 seconds to grab what he drops (if anything) while he screams and bleeds and the screen fades to black. Diablo has no special ability to drop anything better than any of the other monsters though, so don't get your hopes up too high. I did this many times in Diablo, netting maybe 20 items, and of them about 3 or 4 were magical. My best ever was a magical long battle bow, that ID'ed as platinum of giants, as I recall. Nothing worth the effort, in other words.
One little addendum here. Make sure to beware a bug in the game. You can not drink from your belt with the number keys (or a right click) while you have the TK cursor up. So if you are getting hit badly enough that you need a mana refill, you should click on anything to get the TK cursor to go away, drink a potion, and then quickly recast TK.
There is another technique to go through a Town Portal back up to town after Diablo dies but before the game ends, and with it you could then come back down and get anything he dropped, but I honestly don't remember quite how to do it, and it didn't work as well as the TK method anyway.
Of course the simplest way is to play with some other player(s) and have one of them on any level besides 16 when you kill Diablo. Everyone on lvl 16 automatically exits from the game and is taken to the ending movie, but if you are not on lvl 16, (In town = not on lvl 16, btw) you can keep playing without interruption. And then go down to 16 to see what if anything Diablo dropped. The others can rejoin the game after their automatic exit, if they are so inclined.
A note on Apocalypse
Apocalypse is a very useful spell, and it hits for physical damage so can kill any monster, even triple immunes. It can’t be learned in Diablo, so must be cast from staves or scrolls.
The great benefit of Apocalypse in Diablo is that it works over walls and damages anything and everything on the screen. In other words, nothing is immune or resistant to Apocalypse, including your character, though as a physical attack it can be blocked. Amongst monsters, only Diablo casts Apocalypse.
A Mage with a bountiful or otherwise charge-intensive Apocalypse staff can clear out major portions of the toughest monsters very quickly. My only comment on it is, "Cheap, lame, and wimpy". Mages (or the occasional Rogue) who used Apocalypse staves in multi-games I played were almost always those who lacked the skills to kill the monsters for real. Killing tons of stuff over the walls w/o any danger to yourself is not much fun, not very sporting, and not really a tactic I ever saw used much by the higher level chars.
Still, for pure speed, a nice charged up Apocalypse staff left in town and retrieved quickly for some especially tough portion of the game, (perhaps item retrieval after death) can be very useful. I would say don't carry it around normally, though, as it takes the place of 6 full mana pots, and you can do a lot more damage with those pots than with even a bountiful Apocalypse staff in almost every situation.
What to stock in belt and inventory
Blue, blue, and more blue. I usually have 1-6 blue on my belt, with a full yellow in 7 and a Mana Shield scroll in 8, for emergencies. It can be useful to carry a few more full rejuvenation potions, and perhaps some Infravision scrolls in your inventory. Every other spot should be a full mana potion.
One tip for quicker buying at Adria is to use the mouse and return keys. Point the mouse at the 150 blue potion on Adria's list, put your other hand on the return key, and alternate clicks as fast as you can. This will buy them much more quickly than "down, enter, enter".
Also, for fast restocking of your belt, rather than picking potions out of the inventory and trying to click them into the small belt spots, I like to just drop 4 or 5 from inventory to the floor, close the "I" window, and then click them up, letting the auto-belt stocking function put them where I wanted them.
Possible variations in inventory include carrying a CC or KSOH in Inventory for lvl's 15 and 16, (starting with Dreamflange equipped, of course) and maybe an optional jewel or two, depending on how solid your setup is. Often the biggest problem is finding obsidian items with good suffixes, so you might have a crystal/zodiac, ruby/zodiac, and cobalt/wizardry to go with your emerald shield, and would be switching around depending on what sort of projectile monsters you got on each level. (Dog spit is magic, btw.) Other switching options might be an obsidian/wizardry for a dragon/wizardry, where you would use the dragon/wizardry on full melee monster levels and obsidian/wizardry for the resistance when needed.
Try to minimize the switching needed, as it slows you down, and certainly don't do so much switching that you need to return to town to get a new shield or armor for every level. Any time savings there gained by the perfect equipment would likely be offset by the time it took to ascend, change gear, then descend again. Not to mention that this would be terribly bad manners in a Multi-Player game. Also, expert Mages look at trips to town as failures, and hate to go before they are fully dry on blue. The goal on hell difficulty is to get to lvl 16, put a portal somewhere safe, and then fight to the death (or near death, if you consider the no-item drop deaths on lvl 16 to be a sort of cheat) there, taking the shortcut back to town where you can ID the items you have collected and restock on blues enough to finish lvl 16. Frequent trips back to ID stuff become quite rare once your base items are good, as you will generally only collect full plate mail, jewelry, crowns/full helms, tower/gothic shields, and bastard/broad swords. And many of those can be ruled out once you have some of the highest quality items already in your possession, unless you are looking for stuff for other classes or other mage characters, of course.
The Overhead Map
One simple trick with this that some people don't know is that you can move it around with the arrow keys. This is most useful when you have completely or mostly finished a level, but don't remember exactly where the exit was. Rather than teleporting all over the place, you can use your left hand (or the one not on the mouse, if you are a lefty) to very quickly scroll the overhead map and pick out the stairs. Of course since you can't tell the up from the down stairs on the hell map, you'll have to at least remember where you started the level. This is also a useful technique for seeing if you have missed any corners or little interior rooms while clearing the rest of the level.
A couple of useful tables for Sorcerer values.
Max AC needed per Character Level
The way this works is that you can certainly have more AC than this, but this is the most you will have any use for. Essentially any more than this is wasted. At this point the monsters will only be hitting you only with their automatic to/hit (around 25% of the time they swing at you, though this amount varies by Dungeon level). This setting varies slightly between monsters, levels, and difficulty setting, but this is a good general guide.
Max dexterity needed for blocking
What this table means is that you need at least this much dexterity at the listed levels to block every hit you can. You will still get hit (and not block) if the monster swings at you more quickly than you can recover from your block (see discussion of fast block about Stormshield in the shields section). This possibility obviously increases if there are multiple monsters swinging at you at once, as you will block one and not be ready to block the others while you are recovering from the last block. Also note that it is impossible to block most of the time as a Mage. Also note that blocking is only possible while standing still (including engaging in melee combat.) You can’t block if you are walking or casting a spell (which is what you'll almost always be doing, as a Mage.
Exploiting Spell Levels
This is generally considered a cheat, as it involves a game exploit/bug. However, since it's easy to do by accident, I will describe it here. Basically, you can cast a spell, then quickly click on another spell and cast it before your char finishes the spell-casting animation that began with the first selected spell. You will hear the sound and see the casting animation of the first selected spell (say Chain Lightning) but the 2nd spell you selected will be executed (say Fireball). Besides being interesting graphically, you can get into trouble with this by trying to quickly switch from an attack spell to Teleport, and end up standing in the middle of a pack, right where you had aimed that last Fireball. The way the exploit comes into play is that you can cast a spell at an artificially high level. If you have lvl 15 Charged Bolt and lvl 4 Fireball, you can initiate casting Charged Bolt, quickly switch to Fireball, and issue forth a lvl 15 Fireball, since the game is casting lvl 15 Charged Bolt and you are tricking it into casting Fireball. The spell cast is the spell you have most recently clicked since the spell-casting animation began. The level the spell is cast at is determined by the level of the spell you were casting when you began the spell-casting animation. Your character will usually shoot out two of the second spell when you do this trick or accident.