Roc, a bird so huge it can swoop you up and drop you onto nearby hazardous terrain or a trap, or if neither is around, just drop you for some minor fall damage. To avoid the difficulty of adding a “you are being carried by a monster” game state, this should happen in a single turn.

Possibly it should only generate only on outdoor levels, or else be unable to use its pick-up attack on a normal dungeon floor.