Apparently, this ability deals damage before the "Switcheroo" effect happens, so if a targeted baddie dies from the damage, the switcheroo doesn't happen. This complicates things if I'm using the ability to escape being surrounded by monsters. Additionally, if it should happen to stack with the "Defensive Bash" passive ability, the baddie you're meant to switch places with is knocked a space backwards, and you end up moving in that same direction, so no switcherooing ever takes place.
I'm not sure the first point is a bug (any other behavior would be very confusing to mod implementers at least as far as changing when the damage happens), but if it is the way to fix it would be to allow Switcheroo to target corpses, I guess.