The Fourfold Burial Clock
This open dungeon chamber is a timed burial trap. A hovering hourglass governs four concealed sand vents in the walls. Once triggered, the vents pour sand into the room while the hourglass counts down. The hazard rewards quick observation and coordinated action, but panic makes it more dangerous as footing vanishes and the exits become difficult to reach.
The Fourfold Burial Clock
Defenses
Detection
“A brass hourglass hovers at the center of the chamber, suspended without chains or visible support. Its upper bulb is empty, while its lower bulb contains only a thin layer of gray-gold sand. Four circular openings around the walls click open and begin pouring sand whenever the mechanism activates. Fine gears turn behind grates in the walls, and the hourglass rotates slightly whenever a creature struggles against the rising sand.”
Standard Engagement
The trap triggers when a creature touches the hovering hourglass, crosses the chamber's central 10-foot-wide zone, or opens the sealed door on the far side of the room. The trigger can also be activated remotely by a nearby control plate.
On initiative count 20, each active vent pours sand into the room. Four active vents raise the sand by 1 foot per round. Three active vents raise it by 1 foot every 2 rounds. Two active vents raise it by 1 foot every 3 rounds. One active vent raises it by 1 foot every 4 rounds. The vents stop when disabled or when the sand reaches 8 feet deep. At that depth, creatures unable to breathe in the sand begin suffocating.
The hazard resets after 10 minutes once the chamber is empty. The sand retracts through hidden floor grates, the hourglass rights itself, and damaged components repair only if the control panel remains intact.
When the trap triggers, each creature in the room must succeed on a DC 12 Dexterity saving throw or fall prone as the first wave of sand spreads across the floor. On a success, the creature remains standing.
At the end of each round, sand in the chamber rises by 1 foot. A creature can move through sand deeper than half its height only by treating the area as difficult terrain. Once the sand reaches a creature's waist, it must succeed on a DC 12 Strength (Athletics) check as an action to move 5 feet. A creature that fails by 5 or more is restrained until it succeeds on the check or is pulled free.
When the sand reaches a creature's chest, the creature must make a DC 12 Constitution saving throw at the end of each of its turns. On a failure, it gains one level of exhaustion. The creature can hold its breath normally, but speaking verbal spell components while buried is impossible.
Each vent is a separate component. A disabled vent no longer contributes to the sand's rising speed, but its cover remains part of the mechanism and can be used as evidence of the trap's design.
The chamber has a 10-foot-wide central zone beneath the hourglass. A creature that reaches this zone can interact with the hourglass or attempt to study it, but the area is difficult terrain once the sand rises above 1 foot.
When the sand reaches 4 feet, unsecured objects weighing 10 pounds or less are buried. When it reaches 6 feet, doors in the chamber become difficult to open and require a DC 15 Strength check. When it reaches 8 feet, the chamber is fully buried and creatures must begin following the suffocation rules unless they can breathe through the sand.
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