Hm...Ive never lost to a fireball sorceress before with my necro...of course that doesn't mean I've played a _good_ one before either. It's not easy to aim fireballs so usually teeth and the spirit make the difference for me if we're both moving around well and not staying in one place. Meteor is not easy to use in pvp I think unless they're using it to cut you off. If you're wearing an enigma though it shouldnt be too big a deal. If they manage to teleport on top of me and I decide to be stupid and tank, my resists usually make the difference between my spear and her fireball....but yeah you'll want to stack resists at least if not absorb as well in the event they're using facets. A pure f-ball sorceress can do insane amounts of damage...I'm not sure even stacking resists and absorb will protect you quite as much as Sov says if you're going up against a good one but it should give you back a significant edge in damage at least.