Greenvein Pressure Cistern
The Greenvein Pressure Cistern is a compact acid trap designed to punish anyone who disturbs a sealed threshold. Its reservoir slowly feeds corrosive fluid through a glass conduit beneath the floor. When pressure is released, the cistern bursts through hidden nozzles and coats the nearby passage in burning acid.
Greenvein Pressure Cistern
Defenses
Detection
“A thumb-thick glass line runs through the stone like a vein. Inside it, pale green acid creeps toward a sealed ceramic reservoir. Brass teeth and a pressure plate complete the mechanism.”
Standard Engagement
A creature places significant weight on the pressure plate, opens the sealed threshold, or tampers with the brass valve without first disabling the cistern.
When triggered, the cistern sprays acid across a close area centered on the pressure plate, then the exposed conduit continues to leak. The area remains hazardous until the end of the next round. Any creature that moves through it must succeed on a Reflex reaction against difficulty 15 or take 1d6 physical damage and become Burning.
The cistern does not fully reset after firing. After 1 hour, it can discharge a weaker spray if its reservoir was not emptied or disabled. Replacing the reservoir requires specialized alchemical equipment.
The cistern erupts in a close blast around the pressure plate. All creatures in the affected area must make a Reflex reaction against difficulty 16. On a success, they take 2d8 physical damage and mark Stress as the acid spatters their gear. On a failure, they take 3d8 physical damage, mark Stress, and become Burning until they spend an action scraping away the acid or another character helps them. Burning creatures take 1d6 damage at the start of each of their turns.
Acid eats through mundane equipment. A creature that fails the Reflex reaction must choose one exposed nonmagical item it carries. That item becomes damaged and imposes a narrative complication until repaired or replaced. Armor and weapons are not destroyed outright, but the Guide should describe visible corrosion.
The affected area is clearly marked by hissing vapor and glowing droplets. A creature that takes time to move carefully can cross it without rolling, but it must spend an additional action or equivalent movement to do so.
If the hazard is triggered while a creature is standing within close range of the cistern, the Guide may make the acid target that creature first. This is especially appropriate when the creature caused the trigger.
If the conduit is redirected successfully, the hazard can be aimed at a door, lock, hostile creature, or other nearby object. The redirected discharge deals 3d8 physical damage to an object or creature that fails a Reflex reaction against difficulty 16.
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