Hidden Ooze Wall
When a hidden pressure plate registers 30 pounds or more of weight, panels in the ceiling crumble away to drop a massive deadly ooze amidst the party!
Delicate Pressure Plate. Creatures that succeed on an Acrobatics check to perfectly distribute their weight do not activate the pressure plate.
Trap. This trap can be detected by a Perception check to notice the subtle indentation of the pressure plate on the floor all around the coffin in a 10-foot radius that includes the dias it sits upon. If the trap is not detected, it automatically triggers a critical failure.
An Engineering check reveals that the pressure plate is carefully balanced and when trod upon with excellent balance will not trigger. An adventurer can make 1d4 Dexterity checks to wedge daggers beneath the pressure plate before triggering it. Alternatively, a spell able to shape stone can shore up the ceiling to keep the ooze trapped above the chamber.
Critical Failure: The adventurers trigger the trap and are surprised as a gelatinous wall (page 351 in Monstrous Menagerie) drops between them and the chamber’s entrance.
Failure: As a critical failure but the adventurers are not surprised, or the adventurers activate the trap from a safe distance.
Success: The adventurers avoid or disarm the trap.
Critical Success: The adventurers avoid or disarm the trap but have the option to leave the trap active for someone else to deal with.