From Pathfinder #178: Punks in a Powder Keg, which isn't enabled.

Precarious Thunderstone Trap

HAZARD 1

Stealth +5 (trained)

Description A tripwire fastened to the gate snaps when the gate is opened, releasing a moderate thunderstone to the ground.

Disable DC 15 Thievery (trained) to remove the thunderstone or DC 18 Reflex save to catch the falling thunderstone

AC 12; Fort +7, Ref +3

Hardness 3, HP 10 (BT 5); Immunities critical hits, precision

Thunderstone (sonic)

Trigger The front gate is opened

Effect A moderate thunderstone falls on the flagstones and activates, dealing 2 splash sonic splash damage to each creature within 10 feet of the gate. Creatures in the area must succeed at a DC 17 Fortitude saving throw or be Deafened for 1 round. Adjacent creatures can attempt to catch the falling thunderstone (see Disable).

Pathfinder #178: Punks in a Powder KegOGL