Does anyone know if there is a way to deal with area effect spells like stinking cloud or cloudkill? (aside from saving against the magic) Specifically, will potions of magic blocking/resistance work against them?
Or, is there anything that can be done that will work against them 100% of the time (like free action against web, for example)? Just curious. . .

Well, it depends on the sort of damage a spell is doing. Stinking Cloud, for example, requires save vs. poison. Cloudkill requires save vs. death and Fireball - obviously - does fire damage.

In addition, you might find this interesting: you can make a character GET HP back when he's hit by fire! Fire can heal him in other words. In order to do this, you must have the two Rings of Fire Protection, the Helmet of Defense and a Robe of Fire Resistance. You can also use spells or potions, but then it's only temporarly. Well, when you put all the mentioned items on your character (Fighter/Mage probably), you have OVER 100% Fire Resistance, so you actually get healed by it (negative damage, like the Phoenix Guards). Funny, isn't it?

I hope this helps...

Petrarcus ap Bhaal.