Captain America, Living Legend

Vigilance already exempts a creature from tapping to attack, but the second ability goes somewhere the keyword cannot reach: it untaps a creature the first time it becomes tapped for any reason during your turn. Attack with it, tap it for mana, feed it to a convoke or crew cost, fire off a tap ability: whichever comes first, the body stands right back up and is free to do a second job the same turn. That splits a resource most decks treat as one-shot per turn into two. A single tapper removes two blockers; a mana dork pays for a spell and still swings; a crewed vehicle keeps its pilot upright. The one-per-turn clause and the "your turn" window are what keep the whole thing grounded: no untapping on defense, and no infinite loop from re-tapping the same creature over and over. The vigilant 3/4 frame is almost incidental to what the design is actually offering, which is a whole board that effectively taps twice each turn. This rewards go-wide tap-synergy builds and any shell leaning on activated tap abilities, converting a static team into an action-economy engine that doubles your available taps every turn it survives.