So, this thread is an investigation towards whether it is possible to beat BG ee (1, not 2) black pits, using a solo pure arcane spellcaster. My guess, going into this project, is that no, it cannot be done. Sooner or later you will run into a powerful warrior with insane saving throws and magical protection or just a shitton of HP, and thats that. I especially think the fire giant and rakshaasa will be insurmountable obstacle. As it turns out, however, no, wizards really can solo the black pits!!!
We start off with some disclaimers;
1. Has this been done before? Probably. I entered the pits, thinking *I* should beat them using only a wizard. Would kinda spoil the fun if I read someone elses guide beforehand, now would it not? So, if that is my attitude, why did I write this guide? Well, first off to show that it can be done. The solution to all fights are in spoiler tags. You do not need to click them. Secondly, I sometimes like watching people play games on youtube, instead of playing them myself, because I am curious but not curious enough to invest my time. If there are others like me, those people can now read this guide and do not need to try it themselves. Third, why does anyone post anything online, ever, whether they admit it or not? For this --> http://www.urbandictionary.com/define.php?term=e-peen
2. Bards are NOT pure arcane spellcasters. Whatever your counter-argument is, I dismiss it with contempt, because a class that can dualwield bastard swords is NOT a pure arcane spellcaster class. Also evident in that bards use the thief THAC0 level progression. Needless to say - in case the word 'pure' is somehow unclear to you - any multi or dual class is also disqualified. Now, my answer to the question whether a bard or multimage could solo bgee black pits is "I dunno, I havent tried it", but my guess is "Hell yes, especially a blade or kensai mage".
3. This is not a no reload challenge. Personally, I find no reload challenges stupid, because even a high level char could fail a save against finger or death or somesuch by dumb luck... er.. dumb unluck, and then 20-40 hours of precious game play is forever wasted. Also, some of the fights depend on luck, you may need to try them more than once.
4. I play it on core rules, except when leveling, where I flip it to normal to get all my HP:s. I think at least some of the fights are challenging enough this way. But I dont think it is that very very different on harder difficulties, because of wizards reliance on mirror image and stone skin, so I think it should be doable also at higher difficulties. Havent tried it, true, but still. I am also politically opposed to higher difficulties resulting in tougher generic monsters, or weaker PC:s. Higher difficulties should lead to more generic monsters and better AI and never weaker PC:s, although bossmonsters may get a little tougher, some more levels and/or learn some more trix. A simple damage tweak is, I think, just lazyness on the devs part.
5. This is a legit vanilla play. Also, fighting lower tier fights is not permitted. Now, I havent actually attempted a lower tier fight, but I guess you get some gold and XP for that? I consider the XP and gold restrictions as part of the challenge, and while you anyway cannot gain more than 10 levels, you might be more powerful than you are supposed to be, for some of the fights. So, the current fight only. Also, by the time you reach the last fights you will be swimming in gold like Scrooge McDuck anyway.
With that out of the way, lets discuss which pure arcane spellcaster is the best pick;
Dismissed; Blank mage. There is literally no reason to play this! Specialist mages gets a very important +2 to defeat enemy save throws, for certain spells depending on their specialisation, as well as an extra spell per level. Now, they lose access to some spells, but if that bothers you, pick a wild mage!
Dismissed: Sorcerer. That one extra spell per level over specialist mages is not enough of an advantage to compensate for a lack of choice. Note that this deficiency is generally not a thing - just pick the best spells - when you do not solo. To the contrary, it is an advantage, as you never when what you will encounter, and picking the for the moment best spell means you will not "waste" memory slots by occupying them for rarely used spells. Sorcerers just suck in the black pits, and only when they solo.
So, wild mage, specialist mage or dragon disciple then? They all have unique advantages, which in my mind makes them fairly equal;
Specialist mages; That +2 to beat enemy saving throws is a REALLY strong argument.
Wild mage; Can learn spells well above their level, and use them via the wild surge spell.
Dragon disciple; Bonus to armor class, HP, fire resistance and an ability thats kind of like a weak fireball, earned at lvl 3? Hell yes! Also note that the fire breath is AOE, which lets it pass some magical defences, and that it is resolved as a breath attack and not a spell (at least I think so?) which also lets it bypass other magical defences. Unfortunately, the breath attack is a cone, which makes it kind of useless when they surround you, which they do a lot when you solo. A less obvious advantage is that early level you will save gold, as you do not need to buy scrolls to learn spells.
So, what did I pick? Well, despite the crippling access to spells, I still went with Dragon Disciple. Since you solo, your spellcaster will be subjected to melee attacks all the time, and even a bonus of as little as +1 AC means every single attack against you ever made have a 5% less chance of hitting. That quickly stacks and over the course of the black pits alone adds up to houndreds of damage you did NOT receive... and dragon disciples gets a total of +3 AC by level 10. Further, those extra HP means you will survive where lesser spellcasters did not.
Warning: I started writing this before I actually beat the game. Due to a circumstance with the final fight, I am not sure the game is beatable without dragon disciples extra HP.
Race; There are only four races that get spellcaster classes.
Dismissed; Half-elves. Half-elves gets no bonus elves do not get, but suffer the same restrictions on specialist mages.
So, elves, humans and gnomes remains.
Humans: can choose any specialist mage.
Elves: Near immunity to sleep and charm, +1 dex (= +1 AC and to hit with ranged weapons)
Gnomes: Incredible bonus to save vs spells.
Humans are only useful if you want a specialist mage not available to the other races. Yes, elves get -1 con which is very relevant for dragon disciples... however, gnomes cannot be dragon disciples, and you are restricted to 10 levels, so you will only get +1 con for a human, which is 19, and thus still insufficient for regen. But even if you did not, 1 HP regen every turn means your char would have like, at most, 3 or 4 extra HP during the length of one black pits battle = shit! Elf would still be the better choice. So, elf it is then.
Stats; Obviously, you will want 18 str, 19 dex and 15 (you get 1 extra at lvl 5) or 16 con for an elven dragon disciple for the combat bonuses. You will also want 15 charisma, because that is the lowest a sorc can go, which with Friends (see below) gives you 21 charisma, which maximises store discounts, and 9 int, so you can use all scrolls and wands. There are rumors that some scrolls and wands reguire more than 9 int, but I am to lazy to confirm this. Wisdom can be ignored. Thus, you need to roll minimum 77, which should take, like, maybe one reroll... if you did not already get it from the top?
Skills: Daggers is actually a good choice, despite dealing less dmg than staffs, since there are also throwing knives and... wait what? Ok, there arent. Again, there is not really a choice here, you just go with the flow and pick staff.
The first two spells I recommend are Shield and Friends.
I use shield as a buff before EVERY fight in the black pits, and friend before I buy anything.
Alignment: You'd think it wouldn't matter, but some enemy clerics have smite good. Others probably have smite evil. So, you might want to pick neutral, but honestly, those smite goods never dealed enough damage to be decisive, so pick whatever. Ironically, I usually play a chaotic neutral alignment, I only picked good because it felt more appropriate for a rebellious prisoner of the drow.
Name; I named my (female) dragon disciple "Skankeeta", feel free to use that name if you lack for imagination.
Some general hints;
1. The ONE advantage mages have over other classes (except bards) is the ability to use spells and scrolls. Yes, they are expandable. Yes, you do not get unlimited gold in the black pits. But quite frankly, I dont think you can beat the black pits without them. However, do avoid using them for battles where you deem you do not need them, to save gold.
2. Buy premium equipment as soon as you can afford it. Fights get progressively harder so you will likely need to buy that amulett or whatever sooner or later anyways - which would have made the earlier fights where you were counting your gold like some greedy dwarf easier! The stores update twice, get all you can afford as soon as possible - especially if stores have updated twice already. There is nothing more to wait for!
3. This one is obvious, but I still mention it, just in case; buff away right before you talk to Baeloth - that way, you can start the battle using offensive spells. Also, obviously, start buffing with the spell that lasts the longest. I.E stone skin - shield - mirror image - blur. Many spells that in the main game are mostly useless, like blur, are actually good in the pits, simply because you can buff several spells in rapid succesion - compare to a main game encounter, where ramping up all those buffs could mean missing part of or the entire fight.
4. Spell and bash; again obvious, but just in case you were not already aware of this, you can only cast one spell every round, but the rest of the round can be used to bash skulls. Thus, spell, bash, spell takes the same time as spell spell. Also, I am not 100% sure exactly how this works, because often it is even spell, bash, bash, spell, despite the fact that mages only have one attack per round. I think spell rounds are longer than attack rounds or somesuch? Or maybe spells have some kind of "hidden" cooldown? Whatever the case, dont stand around absorbing dmg like a fool, when you could be the one dealing dmg instead!
5. Some spells lock you in place, like burning hands and aganezzars scorcher. Avoid these spells, if able (I mean, some of them are really good, such as the dragon breath ability of dragon disciples). Also avoid, if able, spells with a long casting time, such as armor. Except that armor is a buff spell, so for those it doesnt matter, as they are preferably cast right before you talk to Baeloth... except that shield is vastly superior to armor so there is no reason to use armor. But, you know, keep casting times short.
Finally, and needless to say, the fights can be beaten in any number of ways - I present my solutions.