The circular stone room smells of wet slate and old brass. In its center, a smoky-glass plate sits in a waist-high frame, its branching grooves catching amber light like threads of water. A brass bead waits in a small cup at the upper-left edge; below it, carved arrows point toward a round reservoir while one branch ends in a jagged sink. Each time the plate shifts, the bead gives a bright tick and the grooves hum faintly, as if the chamber is listening for a safe course.
You step into a round chamber that smells of wet stone and tarnished brass. A smoky-glass plate rests in a metal frame at the center, its branching grooves lit by amber lamps. A brass bead sits at the plate's upper edge. One carved symbol resembles a basin; another looks like a jagged hole.
The plate can be tilted with its two handles, and the bead moves when the glass shifts. The brass stylus can nudge it through the grooves. The arrows are visible without a check; the sink and basin are clearly different endpoints.
Let the group experiment freely before calling for checks. If they circle the same wrong branch twice, offer the tier 1 hint or describe the arrows more clearly. Use the time limit only if the scene needs urgency, and never let a failed check block another attempt.
The circular stone room smells of wet slate and old brass. In its center, a smoky-glass plate sits in a waist-high frame, its branching grooves catching amber light like threads of water. A brass bead waits in a small cup at the upper-left edge; below it, carved arrows point toward a round reservoir while one branch ends in a jagged sink. Each time the plate shifts, the bead gives a bright tick and the grooves hum faintly, as if the chamber is listening for a safe course.
The plate's arrows, the bead, and the two distinct endpoints make clear that the challenge is to guide the bead to the reservoir while avoiding the jagged sink. A successful Recall Knowledge check can identify the markings as a practical waterworks diagram.
START: Upper-left cup
Follow the carved arrows as water would flow.
At the first fork, choose a channel that continues downhill.
At the second fork, the right-hand channel reaches the round basin.
The jagged channel drains into darkness. The round basin holds what the mountain must keep.
Goal: Guide the brass bead into the round basin.
The players guide the brass bead from the upper-left starting cup to the round reservoir by tilting the frame or nudging the bead with the stylus. The etched arrows indicate the intended downhill flow; the jagged sink is a dead end, while the basin is the goal. Ask players to describe each tilt or nudge, and resolve uncertain handling with DC 18 Thievery or Crafting checks. On a success, the bead advances through the chosen groove; on a failure, it stays in place, and a critical failure sends it into the sink. The plate ticks at junctions, hums when the bead is on the safe route, and gives a hollow clank near the sink. A wrong turn is recoverable by resetting the bead, so experimentation is encouraged.
The puzzle activates when a creature touches either handle or moves the brass bead from its starting cup.
| DC | Check | What it gives |
|---|---|---|
| 18 | Society or Crafting (Recall Knowledge) | Recall Knowledge about dwarven waterworks or identify that the etched arrows describe flow downhill. Critical success also reveals that the sink mark is a hazard, not a destination. |
| 18 | Perception | Notice that the grooves are sloped and that a small bead will roll along them when the plate is tilted. |
| 18 | Thievery or Crafting | Carefully loosen the plate's catch or improvise a safe way to tilt it. Failure does not trigger a trap, but wastes time. |
No hint given yet.
The bead settles into the basin with a clear silver chime. Water moves behind the wall, the pressure gauge drops, and the Rainward Gate unlocks with a deep, steady rumble.
If the bead drops into the sink, it clatters into a catch drawer and the plate resets after one minute. A pressure valve releases a cold spray: each creature adjacent to the frame attempts a DC 18 Reflex save, taking 1d6 bludgeoning damage on a failure, or no damage on a success. The spray is a warning and inconvenience, not a barrier; the party can try again. After three failed runs, the bead remains in the start cup and the gate can still be opened with a DC 20 Thievery or Crafting check, but doing so costs 10 minutes and alerts nearby creatures.
The dwarven engineer Sella Venn built the Rainward Gate to protect a mountain cistern from floods and saboteurs. Its glass plate taught apprentices to follow water from high ground through safe channels, around a dangerous sink, and into a reservoir. When the cistern was sealed during a siege, the puzzle was left as both a test of engineering judgment and a safeguard against opening the gate in the wrong order.
For a lower-powered party, reduce the failure spray to 1d4 damage and allow the bead to reset automatically. For a more capable party or greater tension, have the gate begin leaking after two failed runs, but keep the alternate Thievery or Crafting bypass available.
Keep the route legible and let players describe their intended movements rather than requiring exact real-world dexterity. The puzzle tests observation and safe routing, not dexterity at the table. Checks should clarify or assist, never replace player reasoning. Give the bead a visible, audible response at each junction.
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