If this thread is in the wrong place, feel free to move it.
Okay, I just had an idea on killing Baal with a particular monster you find in the Crystalline Passage. Now this is just a theory and I haven't tested this yet, so I could be wrong.
If you play as the Paladin and eventually get the Resurrect Uberskill, you can revive most creatures when they die. Well, there's this lovely gigantic creature somewhere in the Crystalline Passage that has the Tremor skill.
I forget what it's called exactly but is it possible to revive a bunch of those critters, travel all the way to where Baal is, and watch them Tremor him to death?