Quote Originally Posted by jiriku View Post
Trap-in-a-trap designs are the BEST! These are the things that will give you a reputation as an Evil Sadistic DM (that's a good thing).

The trap designer can't predict how the first trap might be disarmed, thus it's difficult for him to design a reliable way for the second trap to trigger off the disarming of the first, so I'd recommend against that.

Just give the second trap its own trigger. The fools your PCs will assume they've cleared the room after disarming the first trap and walk right into the second. Your enjoyment will be doubled as they realize they could have found and disarmed the second trap, if only they hadn't been so overconfident.

In general, you can use variations on this idea by combining a simple, obvious trap with a cunning, diabolical trap. For example, put a trigger for a pit trap that occupies half the room near the entrance to a room. Disabling the trap blocks the mechanism so the floor will not collapse. Put a false door at the back of the room, trapped to release a heavier-than air poison gas. The gas WOULD drift down into the pit, but since the players blocked that trap, it fills the room instead. For the piece de resistance, put the actual exit to the room at the bottom of the pit.

Alternately, if you think your suckers players will fall for it, switch the locations of the real and false doors. Anyone who falls in the pit will think he's found a way out, but attempting to open the false door at the bottom of the pit releases poison gas onto his comrades above, and the gas then floats down into the pit where he's at, delivering to him his just reward.
I am in awe of your diabolical-ness. Good thing I have time to adapt a trap in the dungeon my players are currently in; I've just got a run-of-the-mill spell effect trap now. (I don't use traps much, so I'm not as familiar with their workings.) Clearly there is much more potential here.