Switch Effects (attribute: value applied to targets)
Traps & Vents
Vent Payload: Area Effect
With a blob start, the outer actor spreads as a ragged patch: each ring reaches the next tiles at the start chance, minus the decrement per ring, and stops at walls. Leave it blank to fill the radius instead.
Simple Spawn
Spawn density becomes the gas's density: about how many tiles out it creeps from the vent. Leave it blank for the small default spread. Cloud lifetime is how many turns the gas lasts.