I would love the option to select which field, your or your opponents, to play this card on. The only reason I'm suggesting this is because of those players with a death/fire deck. If you have a bonewall, skeletons, and vultures out, and your shield is going to break next turn, but your ROF will do nothing to your opponent, why not play it on yourself?
Edit: This should also apply to the thunderstorm (or whatever it is) card.