Myr Servitor

The recursion engine is the whole design: keep a copy alive through your upkeep and every dead one comes back, including the copies sitting in your opponents' graveyards. That last clause is the wrinkle that turns the card into a puzzle rather than a plain value piece. The trigger is symmetric, so each player's Servitors return, which matters in mirrors and matters more when a board wipe scatters several of the little 1/1 bodies into multiple yards at once: the next upkeep dumps all of them back at the same time, not one at a time over several turns. The whole thing is conditional on one surviving on the battlefield to fire the check, so the engine is only as durable as your last body's ability to dodge removal: kill the final copy before the upkeep trigger and the chain breaks. What you do with the returning stream is left open. The bodies are minimal, but a board that refuses to thin out feeds sacrifice loops, blink fodder, and any payoff that counts creatures entering or leaving. It is built less to attack than to refuse to stay dead, an early experiment in artifact-creature persistence that anticipated the undying and persist mechanics, which later formalized the idea of a creature paying you back after it dies.