The other two songs, Seldom All They Seem and One Last Hope, cost less to play, making it less of a drain if you decide to pay ink instead of having your characters sing them
Clean up after yourself, mind your language given that the game caters to children as well as adults, and just generally be a good citizen
GLEAM AND GLOW is the best healing effect in the game by a mile, allowing you to heal 3 damage (from a single character) and draw 3 cards
Where do you plan on playing these new Crystal cards
Sidequest: Raise a Chocobo's last ability checks at the moment it would trigger to see if you control four or more Birds
As for Standard-viable cards, I could see Cloud, Midgar Mercenary maybe getting some play, since it has a low cost and can tutor for useful tools