The ruin's corridor opens onto a circular chamber smelling of wet stone, old oil, and hot metal. A massive bronze-and-iron door fills the far wall, its surface embossed with interlocking gears whose teeth twitch by a fraction whenever the chamber's deep ticking changes pace. Three waist-high cranks stand beside it, each marked with a different-sized gear; amber light flickers behind a narrow inspection slot, and dust stirs at a floor vent with every heavy click.
You step into a round chamber where a massive bronze door fills the far wall. Gears embossed across it twitch with a slow, uneven tick. Three cranks stand beside the door, each marked with a different-sized gear, and a worn plaque glints above them. Warm air puffs from a floor vent as the mechanism turns somewhere inside the stone.
The three cranks each have four firm clicks, and a tiny sun-arrow marks clockwise. The plaque is readable without a check. Characters who inspect the narrow slot see three pawls; a correct crank setting makes one pawl glow amber and settle with a distinct note.
Let players try sensible ideas without rolling. After the first wrong setting, describe a sharp clank and a brief vent of dust. After a second, the ticking speeds up; offer a tier 1 hint if needed. Use tier 2 or 3 when the group is stalled, not as a penalty.
The ruin's corridor opens onto a circular chamber smelling of wet stone, old oil, and hot metal. A massive bronze-and-iron door fills the far wall, its surface embossed with interlocking gears whose teeth twitch by a fraction whenever the chamber's deep ticking changes pace. Three waist-high cranks stand beside it, each marked with a different-sized gear; amber light flickers behind a narrow inspection slot, and dust stirs at a floor vent with every heavy click.
The plaque and differently sized crank emblems are visible from the entrance. A character examining the lock can see that each crank has four detents and can be turned either way; the sun-arrow marks clockwise.
The little tooth wakes with the sun: one step.
The middle turns against the sun: two steps.
The great follows the sun: three steps.
Set them in this order, then draw the heart outward.
The characters may examine the plaque, cranks, and inspection slot freely; checks reveal extra details but are not required to solve the lock. They must set the small, middle, and great cranks in the plaque's stated order, turning each the indicated number of detents in the indicated direction. Each crank's four detents make a click count easy to track, and the sun-arrow defines clockwise. After each correct setting, the matching pawl glows amber and settles with a distinct note; a wrong setting produces a hard clank and counts toward the three-mistake vent. Once all three pawls are set correctly, the characters pull the central ring to release the door. They can also attempt a plausible tool-based bypass or physical manipulation of the pawls, using the alternate solutions and checks provided.
Touching or turning any crank starts the internal clockwork. The inscription is already visible, and the mechanism does not require a particular character to activate it.
| DC | Check | What it gives |
|---|---|---|
| 13 | Intelligence (Investigation) | Notice that the three crank housings correspond to the small, middle, and great gears named on the plaque, and that each click is a quarter-turn. |
| 14 | Intelligence (Arcana) | Recognize that the sun-marked arrow defines clockwise as the direction of the rising sun, and that the lock gives feedback after each correct setting. |
| 14 | Wisdom (Perception) | Hear that the three crank housings have different pitches and identify which is the small, middle, and great gear. |
No hint given yet.
The three pawls glow amber in sequence. A deep, satisfying clunk travels through the door, the central ring releases, and the massive door rolls aside on hidden counterweights, revealing the passage or chamber beyond.
On the third failed attempt, each creature within 10 feet of the door makes a DC 14 Dexterity saving throw, taking 2d8 bludgeoning damage on a failure or half as much on a success as a piston slams outward. The lock resets, and the door remains usable; the party can try again after the venting stops, but the noise may draw nearby creatures.
The master engineer Vaela Ticktongue built this gate for the Archive of Hours, where records of the kingdom's most dangerous inventions were sealed away. She designed the lock to be operated by trained gearwrights during routine inspections, using a short mnemonic that could survive even if the instruction manual did not. When the ruin was abandoned, the gate's counterweights kept turning, and the lock became the last working part of the archive's defenses.
For a lower-threat group, reduce the vent's damage to 1d8 or have it knock characters prone without dealing damage. For a more capable level 9 party, keep the listed damage and let the noise attract a nearby patrol only if that consequence suits the adventure.
Keep the plaque legible and the crank markings distinct. The solution should come from interpreting the inscription, not from a hidden check. Describe feedback consistently: a correct setting gives an amber glow and a settled note; an incorrect one gives a hard clank. Reward clever physical approaches when they engage with the visible pawls or cranks.
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