So the heroes, being heroes, headed down into the drow-held tunnels to clear the way. Storming the first row of drow barricades was something of a struggle, thanks to a mind flayer and a Lolth's Sting among their ranks . While the drow warriors themselves were not much trouble, the mind flayer's stunning blast took out laurie_robey's sorcerer long enough for the Lolth's Sting to land a good poison-laced sneak attack, which took the sorcerer out for the remainder of the encounter. (She was also later frustrated in another encounter when her fireball got shrugged off due to drow spell resistance -- it wasn't her night!)
Probably the highlight of the evening was a relatively simple trapped, locked gate. In the middle of a corridor, just a metal grate that had obviously been put there by the drow -- it screamed "TRAP!" from every angle, but neither the PC nor NPC rogues in the party could find the trap to disable it. In the end they threw jamesbarrett's fighter at it, who (being a newbie to these things), tapped the gate with the pommel of his sword, setting off the 15d6 cone of cold that filled the whole corridor.
Well, "surviving" a trap is certainly one way to overcome it! One rogue made his save and was untouched, but most of the rest of the party took a pounding, causing much hilarity as the normally laconic-to-the-point-of-being-mute NPC rogue spent ten minutes chewing out the fighter at the top of his lungs.
All in all, a fun night. So I'm glad I could make it happen.
 Yes, it's Pathfinder, but this is still a D&D game.