Umbilicus

Every upkeep, both players face the same toll: cough up 2 life or hand a permanent back to its owner. It looks like even-handed attrition, a soft-lock piece in the mold of the upkeep taxes that punished stalled boards in its era. The evenness is a costume. The player who deploys it builds toward bouncing permanents on purpose: enters-the-battlefield creatures eager to retrigger, sacrifice fodder that wants to come home, lands and artifacts that recur for value. The opponent, lacking that infrastructure, faces a worse menu where the bounce is pure tempo loss and the life payment is pure bleed, so they hemorrhage life keeping their board intact while the deployer banks the same payment and comes out ahead. The 2-life clause is also the pressure valve that keeps this short of a true prison: anyone can buy out of the choice indefinitely, which converts the effect from a lock into a life-total race, and the deployer wants to be the one setting the pace. The mechanical sleight is that a perfectly symmetrical trigger becomes a one-sided recursion engine the moment one side fills its board with permanents that pay off on the way back to hand. Build that side, and the upkeep tax stops being a tax at all.