Nice idea.
The fact that it can counter practically any type of buff-related creature or status effect (ally creatures afflicted by poison, antimatter, and other status effects, enemy growth creatures or ones with mutated/special abilities from Overdrive, Liquid Shadow, Mitosis, BE, etc.) is pretty awesome. The only concern I have is how potent this could be when used with a card like Armagio, because you would basically be healing it +1 after every Gravity Pull (unless that was your intent from the very beginning... XD)