Venom Pool

Stealth +30 (legendary) to distinguish between the hazard and the oozes within it; DC 0 to notice the pool

Disable DC 40 Crafting (master) or DC 42 Survival (legendary) to neutralize the acid while within reach of it. Three successes using either skill (or a combination of both) destroys the hazard.

Deadly Footing The area of the venom pool is difficult terrain, and each creature moving through it takes 10 acid damage for every square of its area that it moves into.

Poison Puff [Reaction]

Routine (2 actions) The hazard uses its first action to spread 10 feet down the hallway in both directions. Once out of the hall, each side spreads in a random direction each round, but they don't go through doors.