E3 — The Twelvefold Sump
S1-E3 · Basement Area 3 · Map Key
The Twelvefold Sump
Twelve stone basins line the flooded chamber. Each holds a thin skin of black water. At the center, something pale shifts beneath the surface whenever a new ripple arrives from the Intake.
The sump is the working floor of the basement machine. Two narrow ledges face one another across the water, making it possible for the party to coordinate from opposite sides while the central pool grows more dangerous.
Map key
| Feature | Contents and use |
|---|---|
| Twelve basin-stones | Each basin bears one ash-mark and receives a matching ripple from S1-E1. The stones are broad enough to set by hand but slick with black water. |
| Opposite ledges | The east and west ledges are safe footing above the flood. A narrow chain between them can be used as a handline, though it sways whenever the submerged thing moves. |
| Central pool | The water is deep enough to hide the drowned ash guardian. A pale hand, broken chain, or white face may appear between ripples before the threat fully surfaces. |
| North drain | When the final matching basin is set, the drain opens and pulls the water toward S1-E4. Until then, it is blocked by a stone plate engraved with the last ash-mark. |
| Waterproof satchel | Wedged beneath the western ledge is a satchel containing chalk, a brass basin token, and two minor healing potions in padded glass tubes. |
Threat in the room
The drowned ash guardian remains below the central pool until the party’s work disturbs it or the flood rises far enough to force it upward. It is a consequence of the room’s pressure, not a mandatory opening fight.
Route: The north passage leads to S1-E4. The party can retreat to S1-E1 or S1-E2 from the side ledges without abandoning the basement sequence.
Challenge 4: Twelvefold Basin Alignment
Primary CheckPerception DC 16 to identify the incoming mark; Thievery, Crafting, or Athletics DC 16 to set its basin.
The party works from opposite ledges while black water carries each mark from the Intake. Each round, identify the mark and set the matching basin-stones. Achieve 6 successes before 3 failures. A failure raises the water and brings the submerged guardian closer; entering the central pool triggers the threat immediately.
Critical SuccessThe final basins glow gray, the water drains toward Area 4, and the submerged threat withdraws unless already engaged.
SuccessThe matched basins glow and the flood recedes one step.
FailureThe water rises, footing becomes difficult, and the guardian moves closer to the surface. Count 1 failure.
Critical FailureThe basin cracks and the central pool erupts. Count 1 failure and trigger the submerged threat immediately.