Coveted Jewel

A rock everyone at the table can technically control. The three-card refill on entry and the tap-for-three-of-one-color ramp would make it a perfectly usable value artifact on their own; the design turns interesting because of the leash attached. Whoever controls it becomes the political center of gravity, because the control clause fires at the worst possible moment for a defender. The trigger resolves during the declare-blockers step: the instant an opponent's attacker is unblocked, before any combat damage is dealt, that player draws three and seizes the Jewel, untapping it in the bargain. There is no damage threshold to survive and no chance to chump after the fact; a single creature you fail to block is the whole transaction. That timing rewires how the board reads. Defending the Jewel means keeping blockers home and pricing every incoming attacker, but the leash never really breaks in your favor: the artifact is leased to you only until the next combat step, and someone always has an unblocked swing available. The result is a passed-around engine deliberately built never to sit still, generating the shifting-alliance friction that group-game design leans on. Nobody wants to hold it when the next attacker declares, and nobody can resist the card advantage while they do. The interesting decisions cluster around when to grab it and how to wall it off, not whether the raw rate is good.