It's hard to tell, particularly if you play it on a field with many creatures, but probably, as people said, you're hitting creatures with something that didn't do anything useful to them. Lobotomy would be one, and gravity pull on multiple creatures on one side would be another; it would only stay on the last one affected, and the rest would look like they hadn't been affected. Also, if there's enough of the same creature, you could conceivably miss a parallel universe landing somewhere, particularly if it created the new creature in the same slot as something it had just killed as well. (i.e. it thunderbolts a skeleton, then PUs another skeleton and creates it where the dead one was)