Does anyone have any tips on beating Irenicus in the last battle in hell?

While Irenicus can be injured by magical weapons in this battle, he cannot be KILLED by them. I hope you have some non-magical arrows, bullets, etc, in your possession. If you have these, this battle is surprisingly easy. Kill the summoned demons first, then you can focus on Jon. I like to let him chase one of my characters around while all the others hit him with regular bullets & arrows.

P.S. Your last opportunity to buy non-magical equipment is outside of the palace in Suldanessar(sp).