Mutational Advantage is a rare Instant card from Secret Lair Drop (SLD), collector number 2454. Current market price: $7.60 (foil $7.58), TCGplayer market prices via Scryfall.
Permanents you control with counters on them gain hexproof and indestructible until end of turn. Prevent all damage that would be dealt to those permanents this turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)