Captivating Crew

Threaten on a stick, with the threaten part bolted to a repeatable engine. The original red borrow effects (Threaten, then Act of Treason) spent a card to steal a creature for a single swing, a one-shot trade you accepted because there was no other way to do it in red. Here the steal lives on a body that survives the turn, so the same effect comes back every untap step as long as you can pay four mana. That changes what the borrow is for: not just a tempo swing or a sacrifice-fodder grab, but a recurring tax on the opponent's best creature, a way to keep pulling their blockers out of the way or feeding them to your own removal turn after turn. The untap-and-haste rider is the standard package that makes a stolen tapped attacker useful immediately, but the sorcery-speed clamp is what holds the design in check: you cannot ambush a creature mid-combat, cannot snatch a blocker after attacks are declared, cannot react to anything on your opponent's turn. The 4/3 frame matters here too. A repeatable steal engine that dies to most removal stays answerable, and a four-power attacker that has to commit to the board to use its ability is exposing itself the same way it exposes you.