Okay, I'm going to flesh my card out a bit.
??? \ ???
7 ? \ 7 ?
9/4 \ 10/4
If this creature is placed in the middle row, this card is placed back in your hand and you regain the quanta spent.
I was thinking maybe Darkness, just for a thematic fit. You could call the creature Coward. I mean, it could be like it doesn't want to go fight unless it knows there's already a pretty good force out there.
The proposed card seems rather winmore, if you can hit that number of creatures odds are you're already winning. If anything only being able to be played in certain slots seems immobile? Water might be a good choice because of the subtle play it has with inundation.
Well, it kind of IS a bit winmore. At the same time, though, there are plenty of ways to make new creatures cheap, especially with Mitosis. (Who knows, maybe someone might even use Deja Vu for once!)