Thanks a lot for your review! Yes I'm planning to upgrade it in the future, but probably as a real life card game.
Leaf was designed to heal actually, I agree with you, they are less useful than others. I will change that in the future. And "Leaf healing fire" makes a lot of sense. I wonder why I didn't think that? I would definitely add that in the next update. Thanks for your game and its meta review. Means a lot for me! Best of luck, cheers! ^^