Ensoul Artifact

The whole gambit rests on a body that does not exist until you build it. An Aura that turns any artifact into a 5/5 is dead weight on its own; the deck around it has to flood the board with cheap, ideally indestructible, ideally evasive permanents that no one would otherwise read as threats. Glint-shrouded equipment, mana rocks, signets, a Darksteel-flavored anything: each becomes a two-card kill that dodges most early removal because the artifact and the Aura arrive a turn apart. That is the design tension the card resolves, and also its liability. The two-for-one only comes from the artifact side: kill the enchanted artifact and both cards go with it, while an answer aimed only at the Aura leaves the artifact behind and trades one-for-one. So the risk is asymmetric, and it points at the thing that was already yours to protect. The payoff is the speed. Five power on the second turn, attached to something that may shrug off Lightning Bolt or block forever, ends games faster than most aggressive starts can. It is a deckbuilding constraint disguised as a removal-magnet Aura: the more your nonland permanents already want to sit on the battlefield doing nothing, the better the trade, which is why it found a home in artifact-aggro shells rather than as a flexible role-player. The line it draws is sharp, and it wants that line settled before the card ever leaves your hand.