Nameless Inversion

The +3/-3 is the entire trick: a number split that reads as a kill spell when you point it at a two- or three-toughness body, and as a surprise combat swing when you hand it to something that survives the toughness hit. Few two-mana instants fold this much into one target, and that pliability is what carried the card past the kindred-tribal era it was built around. The Shapeshifter type line and Changeling clause are not flavor decoration: an instant carrying every creature type satisfies tribal payoffs and any graveyard or hand requirement asking for a specific kind of card, even though the spell does no creaturing on the battlefield. The "loses all creature types" rider then does quiet but real work at instant speed: it can switch off a target's type-matters bonuses and lord buffs before the math resolves, stripping whatever tribal hooks the creature was feeding. There is a catch the changeling text creates on the offense, though. Because the spell is itself every creature type, it cannot legally target a creature with protection from any of them, the same way protection from black walls it. The result is a clean instant-speed answer that doubles as a pump and a tribal enabler, priced as though it only did one of those jobs.