The Constricting Vestibule
A square stone chamber where the walls physically and psychically contract, fueled by a curse that hides the exit as soon as the trap is sprung.
The Constricting Vestibule
Defenses
Detection
“The room is 20 feet square with a high vaulted ceiling. The stone floor is etched with geometric patterns that seem to spiral toward the center, and the walls are decorated with bas-reliefs of giants pressing their hands against the sky.”
Standard Engagement
A creature moves more than 10 feet into the room or closes the entrance door.
The hazard takes 3 actions on its turn. Action 1: The room's walls move inward, shrinking the playable area by 5 feet on all sides. All creatures are pushed toward the center. Action 2: The curse emits a psychic wave of claustrophobia. Action 3: The walls physically grind against any creature caught in the shrinking perimeter.
The trap resets after 1 hour of inactivity, at which point the walls retract and the door reappears.
As soon as the trap triggers, the door through which the players entered vanishes, replaced by seamless stone. This is an illusion. A creature can spend an Interact action to feel for the door and succeed at a DC 20 Perception check to realize it is still there, allowing them to try and force it open.
Each creature in the room must succeed at a DC 19 Will save or become Frightened 1 (or Frightened 2 on a critical failure) as the walls appear to move faster than they actually are.
When the room has shrunk to a 5-foot square, it deals 2d10+10 bludgeoning damage to all creatures within the room every round at the start of its turn.
A creature can use an Athletics check (DC 20) as an action to Brace. On a success, the room's shrinking action is delayed by one action on its next turn. On a critical success, the shrinking is prevented for one full round.
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