I've finished the game for some time now, but I only just finished that FINAL battle, which I must admit was brutal . By some fluke though I also managed to keep Quoris and Karef alive too, which I'm surprised by because Karef sometimes acted a little suicidally (attacking those balors he almost always got more damage then he dished out and tended to stray a bit too far from the rest of the party to help him). I would say that the iron golems are probably the most consistently badass 'creatures' in the game IMO.
I was curious since it took me about 29 hours to get to that point, I was wondering if that was a long time compared to other people or not