Chromium, the Mutable is a mythic Legendary Creature — Elder Dragon card from Core Set 2019 (M19), collector number 214. Current market price: $0.78 (foil $5.76), TCGplayer market prices via Scryfall.
Flash This spell can't be countered. Flying Discard a card: Until end of turn, Chromium becomes a Human with base power and toughness 1/1, loses all abilities, and gains hexproof. It can't be blocked this turn.