Floor_LowerToHighest
From ZDoom Wiki
242:Floor_LowerToHighest (tag, speed, adjust)
tag: Tag of affected sector speed: How quickly the floor moves adjust: Amount of difference from target height + 128
Lowers a tagged sector's floor to the height of the highest surrounding floor + adjust - 128. So if you want the floor to lower to the height of the highest surrounding floor, use an adjust of 128. If you want it to lower to 8 units below the other floor, use an adjust of 120. Similar for other values of adjust. If tag is 0, then the sector on the line's back side is used.

