Same here... I completely side-stepped Iuz. Surrounded Hedrack with my party and beat the crap out of him... he did have a chance to summon Iuz, but he blew it casting some sort of cure spell on himself. A bit cheesy, but I happen to like the frommage. :chew:
Regarding stacking, the SRD section on damage reduction handles it: So most damage reduction doesn't stack, and although you could get really technical and say that multiple castings of stone skin are not "more than one source," I'd say it's pretty plain that it shouldn't stack (engine limitations aside). I think there are feats and such that grant damage reduction that stacks with other damage reduction, but they're specifically noted, and stoneskin isn't one of them.
My barbarian is a god, but I don't think I've ever done more than "hurt" Iuz. Cuthbert saves the day - that's what other gods DO. So I just don't see why we need to bother.
Sorry, but the SRD is VERY clear on this. "If a creature has damage reduction from more than one source, the two forms of damage reduction do not stack. Instead, the creature gets the benefit of the best damage reduction in a given situation. "
Hi I don't know if it is acceptable to RAW or not, but on my last playthrough, I had my wizard create a "Wand of Stoneskin", which he used to cast 12 Stoneskin spells on my Fighter who used Scather to take out Iuz in 2 or 3 rounds. If I remember correctly, the "Vanilla Iuz" only has 70 or so Hit Points, and can be hit by a 10th Level Fighter with decent stats and a decent weapon. The "New and Improved" Iuz has 700+ Hit Points, has a sword that does 30 - 40 Hit Points of damage per hit (and believe me he doesn't miss very often), and has an Armor Class rating of 37 (if I remember correctly). With stats like those, the only way you are going to take out the "new" Iuz in 3 rounds (before Cuthbert shows up) is to use Scather. The Royal Canadian
Apparently, based on discussions from other threads, it is not necessary to use Scather. However, I think there is a general agreement about the necessity of Stoneskin. Edit: Apparently it is this thread. See above.