In fact this work against any unit but with long range it's more easy to organize and get a good setup to do this. But with non long range units it's fine too but more difficult to reach a position where you can start the trick. In fact the key point is related to initiative if you have Magic Spring level 1, at level 2 there's much less problems.
Obviously if you have bear in your army and Cardinal and Gift or Resurrect the key point of any battle isn't to not have loss but to reach a final position where you can apply the trick.
