From Pathfinder #157: Devil at the Dreaming Palace, which isn't enabled.

Gas Trap

COMPLEX HAZARD 5

Stealth +14 (trained) to smell the poison gas or hear it hissing

Description A spring slams and locks the room's door before four hidden gas vents begin pumping poison gas into the chamber.

Disable Four DC 20 Thievery checks to block the gas vents, or a DC 26 Thievery check to unlock the door and escape

AC 10

Hardness 13, HP 52 (BT 26); Immunities precision, critical hits

Toxic Gas

Trigger A creature opens one of the drawers

Effect The door to the room slams shut and locks and the trap rolls initiative. (The trap can also be triggered manually or disarmed from area E30.)

Routine

(1 action) Each round on its initiative count, the trap pumps more toxic gas into the room.

Any breathing creature in the room takes 4d6 poison damage (a successful DC 22 Fortitude save halves the damage taken). If a creature acts before the trap on the first round, it has the option of holding its breath to postpone taking damage from the trap-holding one's breath after the trap's first action has no effect, since the air in the creature's lungs is already tainted. Locating and blocking one of the hidden gas vents reduces the poison damage by 1d6-if all four are blocked, the trap is disabled, though the door remains locked. Otherwise, the trap functions for 1 minute before all the gas is expended and characters in the room cease taking damage, after which the trap ventilates the room for 1 additional minute.

Reset The trap must be manually rearmed by unblocking the vents or replacing the poison gas tank in area E30.

Pathfinder #157: Devil at the Dreaming PalaceOGL