From Pathfinder #183: Field of Maidens, which isn't enabled.

Perilous Flash Flood

COMPLEX HAZARD 10

Stealth +22 (expert)

Description Whether made up of water rushing through the streets that sweeps up dangerous debris along the way or a less natural substance bursting free of its container, this relentless flood batters everything in its path.

Disable Three DC 35 Athletics, DC 35 Crafting, or DC 35 Survival checks to move or construct barricades strong enough to create a shelter from the flood. While this creates a safe place to stand, creatures outside of the barricaded area may still be in danger depending on the nature and the source of the flood.

Burst Free

Trigger A creature or effect breaks the flood's containment.

Effect The hazard rolls initiative as the flood surges forth.

Routine

(1 action) The flood advances forward 60 feet, crashing into all creatures within its area. Each creature must attempt a DC 30 Fortitude save as the floodwaters pummel them and pull them downstream. The amount and type of damage dealt are based on the nature of the flood, and certain types of floods impose additional effects. The turbulent waters mean creatures within the area of the flood must attempt a DC 20 Athletics check to Swim in order to move, and those who do not succeed at a check to Swim each round may drown.

This caustic flood dissolves flesh as it moves, dealing 1d12 bludgeoning damage and 1d12+8 acid damage. Additionally, it deals 2d6 persistent acid damage to creatures who critically fail their Fortitude saves.

Critical Success The creature takes no damage.

Success The creature takes half damage.

Failure The creature takes full damage and is moved 10 feet along with the water.

Critical Failure The creature takes double damage and is moved 20 feet along with the water.

Pathfinder #183: Field of MaidensOGL