Oh, this is cool, I like the mechanic and how it fits Life's theme!
There is one thing though: this is essentially a stackable Eclipse effect that can't be countered by PC. And since the element is Life, having a creature die isn't too consequential, especially if it's the weakest creature (you could have Rustlers and Mitosis or something). Just a thought. Maybe adjust it a little bit? I dunno, it could be OP, it could not be OP.
