does this stack?
if not, your permanent field gets quickly flooded, which means this card is pretty useless (unless it gets automatically destroyed after x turns)
If it does, you can only use the ability once a turn.
if it does, but allows you to use the ability an equal amount of times per turn as the amount of stacks, the
version would make easy otk with double (or even triple) sky blitz.
I think the best solution would be that it doesn't stack, and gets destroyed after 3 turns.