pf2e.fyi
From Pathfinder Dark Archive (Remastered), which isn't enabled.

Entrapping Chair

HAZARD 5
Stealth +16 (0 to notice the chair)
Description A chair on concealed tracks surges forward, knocking a creature into the chair's seat and trapping them in place with clamping armrests.

Disable DC 23 Thievery (expert) to disrupt the tracks

AC 22; Fort +15, Ref +9
Hardness 14, HP 54 (BT 27)

Take a Seat!
Trigger A creature steps on the track

Effect The chair rockets forward along the track and slams into the triggering creature, dealing 3d8 + 15 bludgeoning damage. A creature who succeeds at a DC 22 Reflex save takes no damage and moves out of the chair's path into a random adjacent square not containing the track. A creature who fails this saving throw is knocked into the chair's seat and captured by the armrests, becoming Grabbed (Restrained on a critical failure; Escape).
Reset The trap resets automatically over 2 rounds if the chair is unoccupied.
Pathfinder Dark Archive (Remastered)ORC