Phage the Untouchable is a mythic Legendary Creature — Avatar Minion card from Conspiracy (CNS), collector number 120. Current market price: $16.46 (foil $65.91), TCGplayer market prices via Scryfall.
When Phage enters, if you didn't cast it from your hand, you lose the game. Whenever Phage deals combat damage to a creature, destroy that creature. It can't be regenerated. Whenever Phage deals combat damage to a player, that player loses the game.