...atleast in the early goings of the game, is Polymorph Self. I've got Nalia in my party, and that's all she's good for right now, besides standing back and launching arrows at trolls. I'm in the process of clearing her castle, and it's been a must for taking out those golems. Nalia duel weilding +1 Halberds with an AC of -7
Cast some stoneskin and mirror image before polymorphing, add milk, stir... instant tank.
Dulouz.