mtg background cards Subtype: Background, Colors: Black, 6 What does 'Choose a Background'

You won't gain life

Or the fact that you can transfer Astrologian's Planisphere to a real creature since its an equipment, or to a creature that has synergies with +1/+1 counters placed put on it

Im a fan of protection spells that leave your board stronger than they were before the effect you needed protection from, and thats exactly the Mutational Advantage youre getting

Its a fun and powerful loop

In addition, all these promo cards feature the new golden frames and a rainbow foil treatment that make them quite gorgeous

Through this ability, you can continuously buff up Rex with all sorts of abilities while at the same time permanently removing problematic cards from your opponents graveyard