Treasury Thrull

The recursion clause is the engine, but the body is what makes it a grind machine. A 4/4 that, on every swing, buys back any artifact, creature, or enchantment from the graveyard turns each combat step into a value transaction: chump it, trade it, race it, and the card you lost comes home the next turn. That return is attack-triggered rather than a cast effect, so the loop runs at combat speed and rewards an attrition plan where you are happy to throw bodies away and reclaim them. Extort layered on top makes the card a slow vise: every spell you cast doubles as a drain, and a board built to grind out the long game naturally casts a lot of spells. The keyword and the triggered ability point the same direction, which is rare for a midrange creature carrying two effects that usually pull apart. One refuels the board, the other taxes the opponent's life total while you do it. The price is the tempo: six mana for a 4/4 that does nothing the turn it lands and needs to attack before the recursion pays off. That is the cost of an engine creature rather than a threat, and it asks for a deck patient enough to attack into a value loop rather than close the game outright.