The cavern chamber smells of wet limestone and cold iron. Water spills from cracks in the ceiling and spreads across the uneven floor, already covering your boots. Three bronze levers stand beside a stone tablet, and narrow channels climb the wall at different heights. Blue light pulses through grooves around a massive stone door; with each pulse, its bronze bolt shudders, while a barred drain gurgles beneath the rising water.
You step into a cavern chamber as cold water pours from cracks in the ceiling. Three bronze levers stand beside a worn tablet. Across the room, blue light pulses around a stone door, and a barred drain gurgles under the rising water.
The levers bear low, middle, and high channel marks, and each is currently sealed. The tablet is readable. The door's bolt gives a muted clunk whenever the water surges. Characters can inspect, test, or operate the apparatus without special tools.
Give the tablet and channel heights plainly. After one wrong sequence, describe the feedback and allow a fresh attempt. Offer tier 1 if players debate without testing; use tier 2 after a second failed attempt and tier 3 when the water reaches chest height.
The cavern chamber smells of wet limestone and cold iron. Water spills from cracks in the ceiling and spreads across the uneven floor, already covering your boots. Three bronze levers stand beside a stone tablet, and narrow channels climb the wall at different heights. Blue light pulses through grooves around a massive stone door; with each pulse, its bronze bolt shudders, while a barred drain gurgles beneath the rising water.
The door's bolt shudders in time with the blue ward-light. The tablet and the differently placed channels make clear that the levers control the door's pressure lock.
Warden's operating verse
First wake the water in the lowest stone. Let the middle answer when the first has sung. Last loose the crown above them both. When all three voices rise, turn the hand of bronze.
The party has six rounds from entry before the water reaches the ceiling; each round is approximately six seconds, and characters can act normally while it rises. Opening the levers in the wrong order makes the mechanism clang, sprays the operator, resets all levers to SEALED, and costs one round. The correct sequence is low channel, middle channel, then high channel, followed by turning the release wheel. Each correctly opened lever gives an audible rising tone and sends a visible thread of blue light toward the door; a wrong lever makes the light gutter and the bolt knock once. A character can use an action to operate a lever or the wheel. Checks can reveal clues but are not required, and a failed ability check should not conceal information already visible in the room.
Crossing the threshold breaks a brittle ward-seal. Water begins pouring from the ceiling cracks, starting the six-round timer and activating the door mechanism.
| DC | Check | What it gives |
|---|---|---|
| 12 | Investigation | Notice that the three levers connect to channels at different heights and that the lowest channel is nearest the door bolt's counterweight. |
| 12 | Arcana | Recognize that the blue lines are a pressure ward, not a general magical lock; it responds to the sluice levers being moved in sequence. |
| 10 | Perception | Hear the distinct low, middle, and high tones the channels make when water reaches them, matching the inscription's 'sings' to the mechanism. |
| 13 | Athletics | Hold a jammed lever in position while another character resets or works the mechanism; on a success, prevent a failed attempt from advancing the flood. |
No hint given yet.
The three channels ring in ascending tones. Blue light converges on the bronze bolt, which slides back with a deep grinding sound. The stone door opens, and the barred drain pulls the floodwater down to ankle height over the next minute.
A wrong sequence produces a loud clang, sprays the operator with water, and advances the flood by one round; all levers return to SEALED. If the water reaches the ceiling, the chamber fills, but the door's ward releases under the pressure after 1 minute. Characters must swim through the doorway and make DC 10 Strength (Athletics) checks to avoid being swept against the stonework; failure deals 1d6 bludgeoning damage, but the party can continue the adventure.
The wardens of Keldrun built this cavern lock to protect a buried spring from raiders and to keep its pressure from flooding the lower mine. Their masons shaped three sluice channels at ascending heights and taught initiates to open them in order, from the lowest channel to the highest, before releasing the door bolt. Centuries later, the ward still recognizes the sequence, though its warning bell and drainage system have weakened.
For a larger or more experienced party, start the water at knee height and allow only four rounds before it reaches the ceiling. For a smaller or less experienced party, give eight rounds and have the ward-light visibly mark the correct next lever after the first failed attempt.
Keep the control labels and the tablet visible. The puzzle is about interpreting and testing the sequence, not guessing hidden rules. Let players describe sensible physical approaches; reward them with information or progress even when a roll fails. The flooding should create urgency without stopping discussion or removing agency.
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