Drowning Chamber Trap CR 9
When the trap is triggered, the doors to the drowning chamber instantly close and seal. A round later, the room begins filling with water. Five rounds later, the room is completely filled with water. The room stays filled with water for four minutes at which point the water drains out and the doors open. The hidden switch bypass shuts off the water, opens the draining holes and the doors leading out.
Liquid (water); never miss; onset delay (1 round) multiple targets (all targets in a 10-ft.-by-10-ft. room)
Skill Craft (traps) DC 25; Cost 9,000 gp
Riyal’s Research: Traps. Copyright 2012, Jon Brazer Enterprises. Author: Dale C. McCoy, Jr..