Since you're already gonna be under Protection from Evil, the Cleric's level 9 spells don't look too bad anymore, do they?
I&M can't use Protection From Evil, so no worries about the monsters standing idle. If you keep them busy enough with summons, Undead, Demons and the like, you can clean the whole room out in under a minute without getting more than a scratch.
Holy Word is your best friend here. An instant cast spell, that enables you to cast Mass Heal with enemies standing around, being hacked apart. Most usefull if you have a party full of spellcasters, like I am just playing now. The thing works better than Timestop, because it allows every partymember(unless they're evil) to cast spells/attack/use abilities...
And for those of you who are not avare of it, there is an alternative to tainting the pool. Instead of fighting the avatar of Iyachtu Xvim, you can make a deal with him: in the final battle, the enemies can't summon monsters/undead/demons or anything. But they keep the healing of the Pool. IMHO, the no summons part is better than the no healing pool, but I always taint the pool. MAking deals with Chaotic Evil Gods doesn't sound like my thing.. [img]smile.gif[/img]