I love Grimtooth.
If you haven't heard of Grimtooth, shame on you! First published back in 1981, the Grimtooth's Traps series has been scaring PCs for over 30 years now. You don't even need to use any of the traps - just setting a copy on the table in your stack of monstrous compendiums and DMs Guides is enough to keep most parties creeping through the dungeons one skill check at a time.
Or poking doors with sticks.
An illithid had just ripped a dwarven temple out of the side of a mountain, turning it into a massive stone golem. The PCs stopped it, but not before it completed it's nefarious work, sending some blast of energy into the sky. The dwarven temple guard had noticed that a gem, used to power the statue of Moradin that flowed with Holy Beer, had been taken before the attack, and sent the group into a hole in the side of the mountain, exposed after the debacle, reasoning that since the stone wasn't in the wreckage of the temple, something must have grabbed it and slid back down into the darkness in the confusion.
Once again feeling their oats, and accompanied by their NPC siblings, they sauntered down into the darkness. The thief was doing his thiefy things, checking each door for traps, and disarming them, but then they came to the Dead End. There were doors on either side. Only the door on the left wasn't a door at all, as the thief found out when he failed his detect traps roll - someone had smeared a jelly of animal control on the wall in the shape of a door, glued a doorknob onto it, and summoned a swarm of bees, which had waited patiently for an adventuring party to stumble across them. The bees swarmed, and several people were stung, causing them to take a -1 penalty to their Dexterity, as their fingers swelled up like sausages.
The party was, to say the least, traumatized, and was practically poking doors with sticks for the rest of the night. They found potions, and checked to make sure there weren't bees in them. They climbed a ladder, but not before making sure the rungs were not, in fact, bees. Phantom bees lurked everywhere for the rest of the night, and likely haunted their dreams after they left.
Oh, and the other door? That was made of a flimsy glass like substance which shattered when the fighter yanked the door open, spraying the party with acid. There were deadfalls, tripwires and lots of other nasty traps all over the place, but nothing affected the party as viscerally as the bees did, for some reason.
And that was out of
Grimtooth's Traps LITE, described as, "kinder, gentler traps".
Heh heh. I can't wait to break out the REALLY nasty stuff.
