So I didn't see a thread about this yet. I'm late to the party (didn't notice the beta) and sort of mediocre, but I can sometimes beat Vicious dungeons if I feel up to it. Anyway...
* I feel like Halfling and Gnome should work, but I am really bad at these races. I sort of realize that you can't just endgame-spike off of a surplus, but my instincts keep telling me not to chug the damned things! I was hardly able to beat Grim's Grotto with a Halfling Chemist because suddenly I'm Level 6 with only 8-10 black squares left... X-D
* Orc is a no brainer! Bysseps spam and conversion bonuses, and you're basically Orc-Human 24/7. It's like Taurog Berserker with more spell casting. More worthy foes will force you to think about how much you cast Bysseps per hit, though. Once per hit? Twice per hit? Are you regen-fighting in Health mode?
* Dwarf worked better for me than Halfling. I wanted to take the boss on early as a Halfling with Martyr Wraps, but tanking just a single hit slows you down. This sort of tactic is more doable as a Dwarf. Do you really need to pop a health potion once per level? Probably not... So why not Dwarf?
* Human doesn't sound that good to me, at least not with Bysseps spam. Maybe there's some cool Health Regen Mode strat, though.
* Elf might be able to milk an extra Bysseps, but you'd probably rather be an Orc who worships Mystera or JJ...
* Goblin - Not sure how this is supposed to work. Maybe I just shouldn't think about it too hard. Spike the boss with level-ups and triple Bysseps attacks?
* Binlor! I think Stone Form procs only if you have zero might stacks, whereas Bysseps can be stacked regardless. The good news is that Stone Form does NOT increase the cost of Bysseps. So for your first stack, Pisorf/BearMace/StoneFist/Endiswall/(Binlor boon), and THEN start Bysseps. I'm not sure whether this is an exploit, or if it's Working As Intended, but I don't think it's that broken. (Or is it?)
* Earthmother lets you spike mana while in Health Mode. The other boons work well too, and the Entanglement for the last hit on the boss can turn a close fight. This saved my Halfling run - Corrosion-enhanced Pisorf fueled by Earthmother.
* TT - You can leverage the Reflexes a little better than your average class. When you have a Dodge ready, you can go ahead and bulk up.
* JJ/Mystera - Hit 16 mana, guaranteed.
* Taurog - Ok, it sounds bad, but you can probably get away with it. Lay off the Bysseps a little, and you can have a piety buffer for the boss fight.
Dracul - Might not be bad? Health Mode is discouraged, but Mana Mode can be compensated somewhat with pools and lifesteal. I could potentially see saving popcorn, burning health potions early, and joining late for the spike.
GG - Ewww, potion hater. Humility is just as strong as ever, though. Is it worth giving up on potions? Maybe.
Bludtopowa and Halpmeh can iron out Health/Mana mode into a flexible "regenerate what you need" mode, if either drops. You can't plan on them dropping, but it's worth noticing if they do.