I can definitely say that the life-gravity elephant idea itself is not new (can't link-fetch right now though).
The ability is well-balanced for the elements that it's in, since neither have set damage CC, so it would require a trio or greater for extra smoothness of using Stomp. I also think that Angry Elephant + Oty would be a really strong combo, although a bit expensive.
I didn't see it in the notes, so what happens when there's a tie for lowest HP?