For a long time, my monk was thwocked around too, but by level 16 she had a -6, -7 AC and eventually ended up with a -9 and I got thwacked a lot less. Plus, I was attacking so often doing so much damage and stunning my opponents that I could take down Adamantite Golems, Elder Orbs and Pit Fiends more or less by myself at the end of the game.
I would certainly hope the monk would get more abilities....more attacks, etc. etc. in Throne of Bhaal. But then again, beats me
