Nice way too put it Nazu. I think the patch for PC might be good, coz the final boss on Normal on the Xbox wasnt even possible. I had to do it on "Casual". However there's a trick.. Read below.
End battle spoiler:
[bgcolor=black]Ionno if this always works, but using the huge mounted crossbow things, you can time the shots and make the Archdeamon freeze, stopping it from shooting those dark thingies at you. Until it completely is out of life. Just make sure you kill all the minions or carry around a shitload of potions. My entire squad was dead so I had to do this on my own, but once you got the hang of it it was as easy as stealing candy from a kid in a diaper.[/color]