Jmizzle, do you have access to some sort of beta version of the new cards? Because I don't see them in the game yet...
Yeah, unlimited HP is problematic, especially with Miracles. But in my opinion, a cap of 50 is a bit too low. Might be better if the cap is 100; or, you can make the upgraded version capped at 100.
EDIT: OK, nevermind. I just saw the trainer.