[Morgeruat]

I always like stinking cloud, since I think the spiders are immune to web, cast stinking cloud, in the center of the group of them, then soften them up with either fireballs or wands of fire.

A tank with boots of speed is essential, mostly in order to keep the spiders away from your spell lobbers. A your cleric needs to be casting defensive harmony, chant and any other spells that stack for better AC/THAC0 (preferably before you go into the lair), other than that, be prepared to reload and keep slugging away. (I tended to send minsc in with the boots of speed as soon as the spider chick is dead to grab spiders bane and then go nuts, a tactic that works well in PnP D&D as well, go for the hoard before going for the monsters you can't hurt).