How about you make the ability usable multiple times per turn, but once you pick a creature, you can only use the ability on that creature this turn. So you could only kill on creature per turn. You would still get to pwn the opponents dragon, but you couldn't kill all of their dragons, even if you had multiple Ignite Ones out on the field.
I don't know how to explain this concept. It's like, you target the opponent's emerald dragon and kill with using ignite one's ability, but you can't target any other creatures, even if you have another ignite one on the field. I'm trying to take a leaf out of the rustler's book. If you have more than one rustler on the field, it's kind of useless.
Oh and for whoever said something about SoR. Whenever an ability can be used multiple times, SoR makes it so that the ability can only be used once per turn. Rustlers only make 2 life quanta per turn for free if you SoR them.
