Xyru Specter is a rare Summon — Specter card from Mystery Booster Playtest Cards 2019 (CMB1), collector number 51. Current market price: $0.45, TCGplayer market prices via Scryfall.
Flying Whenever Xyru Specter deals damage to an opponent, that player discards a card unless they challenge you. If challenged, and you show them two black cards in your hand, they must discard two cards.