Shield Broker

The clever part is that the theft and the protection are the same counter. Most blue control-magic effects are auras or one-shot enchantments that end when they leave the battlefield; here the shield counter does double duty, marking the creature as yours while functioning as the exact thing that keeps it yours. Break the counter (deal it damage, hit it with removal, or trigger any effect that would strip it) and the loaned creature snaps back to its owner. That single-use damage shield is a familiar keyword, but bolting control-magic onto it inverts the usual math: the shield is normally a gift to the creature's controller, and here it is the leash. What makes this design cohere is durability. Steal effects that end on a wipe or a bounce ask you to protect the stolen thing forever; this one hands the opponent the tool to undo the theft, so the counter is both the reward and the ticking clock. It also politely refuses to touch commanders, targeting only a noncommander creature you don't control, a self-imposed restriction that keeps the effect from becoming a hard answer to the format's most valuable permanent. The 3/4 body is beside the point; the octopus is a delivery mechanism for a piece of temporary theft that carries its own expiration date printed into the very counter that enables it.