On a level where you can knock opponents off an edge (not stairs) perform any version of the Izuna drop (hold or counter hold) next to the edge. If you pull off the whole thing, there is a chance you might do the move off the edge. This does massive damage, depending on the height of the fall, it can take off a half of a full health bar. (Too bad it's harder to pull off the Izuna drop in DOA Ultimate than in DOA 3).