I'm pretty sure you can use Stone Curse on him. I just ran into Rustweaver (Doom Knight) and he was immune to Lightning and Fire, so I Stone Cursed him and just started wailing. I have 100% accuracy, I kind of wanted to be a fighter mage.
I knew I should have grabbed that King's staff of brilliance I saw. +30 magic on that thing too, but I didn't see a point in replacing my current staff of brilliance that has +30 magic on it.
Bah, the hack won't seem to work to change the difficulty to hell, I even attempted to make my own hack with the bit of game hacking knowledge that I have, but what I managed barely worked and was buggy. I ended up installing hellfire and transfering my character over, who is now naked.
I would almost prefer to transfer him to multiplayer and play him there, but I hate not having quests in the game other than the very basic ones.