Mind Control

Threaten and Act of Treason borrow a creature for one attack and hand it back at end of turn; this is the steal that sticks. The Aura takes the enchanted creature and holds it as long as the enchantment survives, which reframes theft as a permanent rather than a one-shot. That reframe carries the whole cost structure. Five mana and the loss of card-economy that comes with committing to a permanent buy you indefinite control, but they also leave the theft sitting on the battlefield where any disenchant effect can answer it, returning the creature to its owner the instant the Aura dies. Temporary control spells can never be undone after they resolve; this one stays exposed for the rest of the game. Wing it onto an opposing threat and you have not only blunted their best attacker, you have flipped it onto them, swinging the board by two creatures' worth of tempo in a single resolution. The cost of that swing is that someone else always gets a vote on whether it stays. It is the blue answer to what it takes to make a borrowed creature your own forever: a fragile permanent, paid up front, that the opponent can pry back if they brought the right tool.