Many of the best traps are simple. You just have to think about it, and hope your victim doesn't.
Rick Riordan"Bloated!" he cried. The corresponding hieroglyph flew through the air, bursting against a demon's chest in a spray of light. Instantly, the demon swelled like a water balloon and rolled screaming down the pyramid. "Flat!" Thoth blasted another demon, who collapsed and shriveled into a monster-shaped doormat. "Intestinal problems!" Thoth yelled. The poor demon who got zapped with that one turned green and doubled over.
Rick Riordan