Oracle

Every turn, for no cost, this avatar lets its controller swing with a creature and then snatch it back out of combat before damage resolves: untap the attacker, pull it from the red zone, and walk away clean. That repeatability is the whole point. The Vanguard format attached a single persistent ability to the player as a fixed trait of the seat, which meant an effect like this was never rationed by the usual card economy that governs combat tricks. There was no spell to spend, no creature to tap, no resource clock counting down. The result is a permanent pressure valve on combat math: commit to an attack to force damage or bait a block, then reclaim the creature if the trade goes wrong, free, every combat, all game. Vanguard ran as a casual side product, never a constructed pillar, and that sandbox status is exactly why an effect this open-ended could exist. With no metagame to warp, the design could ask a blunt question: how much does the attacking step distort when one side can always retreat a single creature at will and without paying for the privilege.