Reins of Power

Borrow the whole board, swing, and hand it back: that is the trick most swap effects never pull off cleanly. Where a Threaten effect trades your card away for a single creature, this loans everyone their full board for exactly one turn, with haste so the borrowed army acts immediately rather than sitting summoning-sick. What it buys is a one-turn reversal of the entire battlefield, and what that reversal does depends on whose turn it is. On your own turn, cast it and swing with the opponent's army: their finishers attack into a player who no longer controls a single blocker that matters. On their turn it functions as a Fog with consequences, because gaining control of an attacking creature pulls it out of combat entirely; cast it in response to a swing and the attack simply ends, with the attackers now standing on your side of the table. The temporary control clause is the leash on all of this: the creatures walk home at end of turn, so the play is a swing in initiative, not permanent theft. You have one turn to convert the borrowed board into something irreversible (combat damage, a sacrifice payoff, a tutored win) before everything reverts and you are left holding only what was handed to you. A perfectly symmetrical effect engineered to be cast asymmetrically, and the reason it has remained a cult-favorite blue trick for decades.