Etrata, Deadly Fugitive

The 1/4 deathtouch body is the tell that this is a control piece wearing an assassin's face: it wants to sit back, block, and turn the opponent's own library into a resource. The engine runs on two interlocking parts. Combat damage from any Assassin you control cloaks the top card of that player's library, stranding their next draw as a facedown creature already under your control. Every facedown creature you control (including the ones just lifted off the top of an enemy deck) gets an outlet: pay to turn it face up. That is a status change, not a zone change, so a cloaked creature simply becomes what it is with no fresh enter-the-battlefield trigger, and a cloaked land reveals itself in place. The seam is what a card cannot become. Instants and sorceries have no face-up state, so instead of flipping they are exiled and you may cast them free; a burn spell the opponent would have pointed at you becomes yours to fire back. A cloaked planeswalker technically flips face up, but since turning face up is not entering the battlefield it arrives with zero loyalty and dies to state-based actions before it does anything, so those are dead loot, not stolen threats. The trick threads a needle mill-and-steal effects usually miss: rather than dumping cards into a graveyard you then have to enable, it seizes the top of the library the moment damage connects, and hands you an on-card way to spend the take.