Every Magic: The Gathering FINAL FANTASY Play Booster contains an art card (which you can learn more about here) or a non-foil double-sided token featuring one of the set's 23 full-art tokens or the emblem created by Sephiroth, One-Winged Angel on each side
Each iteration resets the board to its original state, so you'll need a way to get some value out of the loop
(8/7/2020) Players can't move cards between their deck and sideboard before the new game
The commander's color identity rule assigns one of the most possible versatile color combinations with blue, black and green
Not background necessarily, but some other line of text that says something along the lines of Whenever you sacrifice a Treasure token, give a creature a +1/+1 counter and trample until end of turn. That would make it a lot more interesting and powerful, but I suppose not every card needs to be great
Two shiny gold stars: Special Illustration Rare