Source: Pathfinder Adventure Path #34
The “floor” of this area is the smooth upper portion of a circular disc balanced on a pivot. When any creature steps into the room, the floor underfoot shifts downward under the creature’s weight while rising up at the far side of the room. By moving around the room, one can control the angle of the floor’s tilt. Standing exactly in the center allows the floor to return to level, as would placing two objects of equal weight on opposite sides of the room, in theory. Unfortunately, the pivot on which the disk balances is itself unstable, causing the floor to wobble and shake even when the characters take care to keep things as balanced as possible.
Navigating the room when the disc isn’t balanced is nearly impossible without flight. The walls and floor offer no handholds for climbing—only by moving along the edges to manipulate the floor’s angle can creatures move through the room. Doing so requires a DC 20 Acrobatics check each round, and the floor is treated as difficult terrain. Further complicating the issue is the fact that spiked pits lie in wait to the north and south—anytime a creature moving through the room fails its Acrobatics check, it must make a DC 15 Reflex save to avoid rolling into one of these two pits. Each pit is 50 feet deep and lined with spikes.
Trigger location; Reset automatic
Effect pivoting floor (see above); 2 50-ft.-deep spiked pits (5d6 falling damage; pit spikes Atk +15 melee, 1d4 spikes per target for 1d6+5 damage each); DC 15 Reflex avoids; multiple targets (all creatures in area D6)