The Spider Cave is a long wide cave in the Fissure of Woe that runs from the Temple of War southeast to the Fissure Shore. The cave is literally crawling with Armored Cave Spiders who remain hidden until a party approaches them and then descend from the ceiling. The occasional Doubter's Dryder appears every now and then.
The cave seems to be the sewage system of the Temple of War, and it is there that the invading Shadow Army places the Seeds of Corruption to taint the flames of the forge within the temple. Destroying these seeds throughout the cave is the objective of the quest Restore the Temple of War.
The Spider Cave has achieved near legendary status among adventurers in the Fissure because of its entrance by the shore. Killing the Dryders at that entrance will trigger more than a dozen Armored Cave Spiders to descend and overwhelm the party. The Dryders and spiders are linked as follows: Upon aggroing a Dryder, a group of three spiders will dangle from the ceiling right in front of it and another will come down behind it but after a short delay. The back group will usually rush to where the Dryder was and sometimes can surprise a party still engaging the front group.