Crosis, the Purger is a rare Legendary Creature — Dragon card from Invasion (INV), collector number 242. Current market price: $4.56 (foil $199.62), TCGplayer market prices via Scryfall.
Flying Whenever Crosis deals combat damage to a player, you may pay {2}{B}. If you do, choose a color, then that player reveals their hand and discards all cards of that color.