Floor_LowerToLowestTxTy
From ZDoom Wiki
241:Floor_LowerToLowestTxTy (tag, speed)
tag: Tag of affected sector speed: How quickly the floor moves
Lowers a tagged sector's floor to the height of the lowest surrounding floor and uses the trigger change model to give it a new picture and special. If tag is 0, then the sector on the line's back side is used.

