Void Stalker

The activated ability is an answer that refuses to play the destruction game. It does not kill the target; it puts the creature on top of its owner's library and shuffles, randomizing it back into the deck. Library-tuck sidesteps every defense that destruction respects: indestructible threats, regenerators, anything carrying a punishing death trigger. None of them ever dies, none of them reaches the graveyard, so none of those protections matter. The price is steep and symmetric. The ability costs plus the tap, and it returns the Stalker itself onto your library alongside the target, so each activation spends the body that powers it: one clean answer, then your own 2/1 goes back too. Both players reshuffle, so neither the tucked threat nor the spent Stalker has a guaranteed return; you are trading a two-mana creature for a one-shot eraser and accepting that you have randomized both away. That it taps does not pin it to your own turn: this fires at instant speed, holding up the answer to ambush a creature mid-combat or in response to a pump spell. The 2/1 frame tells the rest of the story. It is built to come down early, trade or chip in, then convert into a reset button the moment a problem lands. Tuck effects that answer the unanswerable are usually noncreature spells; the unusual move here is riding the eraser on a body you can deploy on turn two.