I just finished a game with the Torchbearer. At one point, I used the Fire Nova ability to send a group of creeps flying. One of them went over the edge and didn't seem to die right away. My Torchbearer and an allied AI Regulus sent a few shots at it, aimed straight down. Mine were crashing into the ground, but Regulus's crossbow was over the edge and was actually firing down at it. After a few seconds, the Regulus decided to use Angelic Fury to take care of it. I don't know if the creep was eventually killed from the fall, from Regulus's shots, or from the Angelic Fury, but it did die.
It only took a few seconds, and I didn't manage get a good camera angle to see exactly where the creep went other than "off the edge". It was a hole in the middle of the stage (opposed to one of the sides). Unfortunately, the replay freezes at an unrelated part (Poita's unofficial replay viewer) so I couldn't go back and see exactly what happened.