Would it be possible for a reverse falling floor?

sure...make the first combo a pit or gap or whatever you want it to be and then copy that combo a bunch of times..then make a series of tiles to make an animation sequence that look like the rising floor & then make a combo of that and link the pit combo to the rising floor combo & then click the rising floor combo to a regular, walkable floor combo

Cool, cuz i was thinking of an effect almost like a mix of Indiana jones and the Last crusade mixed with a bit of X-Men magneto things from the movie.