Etrata, the Silencer
Legendary Creature - Vampire Assassin | Power/Toughness: 3 / 5 (CMC 4)
Etrata, the Silencer can't be blocked.
Whenever Etrata deals combat damage to a player, exile target creature that player controls and put a hit counter on that card. That player loses the game if they own three or more exiled cards with hit counters on them. Etrata's owner shuffles Etrata into their library.