Xathrid Slyblade is a uncommon Creature — Human Assassin card from Magic 2015 (M15), collector number 124. Current market price: $0.10 (foil $0.52), TCGplayer market prices via Scryfall.
Hexproof (This creature can't be the target of spells or abilities your opponents control.) {3}{B}: Until end of turn, this creature loses hexproof and gains first strike and deathtouch. (It deals combat damage before creatures without first strike. Any amount of damage it deals to a creature is enough to destroy it.)