I don't think it costs too little, as it it pretty much only viable in mono decks.
When considering whether abilities are OP, the dragon's HP must be taken into consideration. For example, although the
ability seems OP, the dragon is incredibly fragile (3/2 HP). Massive Dragon, on the other hand, has 30 HP (I'm not sure about how balanced the ability is).
I do think that it should use effects already in-game (in reference to
and
). Maybe Regenerate and Rewind, respectively?
seems a bit OP compared to
, how about Holy Flash?
could be Chaos Seed (but what it has now is fine, too).
Nevertheless, I love the idea.