Wrangle

The cap is the discount made legal. Threaten-style theft spells have always wrestled with one tension: a steal-and-swing effect that grabs anything is a removal spell in disguise (take it, attack, sacrifice it), so the bigger the legal target, the more lopsided the swing. The standard members of this lineage pay three mana for unrestricted access; this one shaves a mana off and pays for the discount by capping the target at power four. That trade is the whole design. You give up the ability to commandeer the opponent's haymaker for a lethal turn, and in exchange you get a sorcery that costs the same as a cheap removal spell. The untap-and-haste package is the usual sweetener that makes any theft spell worth a card slot: you can swing with a tapped blocker, push a freshly resolved body, and use the borrowed creature the instant it changes hands. Where this differs from the older unrestricted designs is both the price and the ceiling, and the two are inseparable: the restriction is what justifies the cheaper rate, not a tax bolted onto an identical card. The four-power line rarely bites in a deck stocked with sacrifice outlets and combat tricks, where the creatures worth stealing tend to sit under the cap anyway, and the saved mana opens room for the second spell that turns a borrowed attacker into a permanent loss for the opponent.