Drana, Kalastria Bloodchief

A removal spell that pays for itself by stealing the toughness it strips. The -0/-X half is the kill button: feed it enough mana and any creature shrinks toward zero toughness and dies. The +X/+0 half is the coupling that separates this from a clean point-and-shoot effect, because the buff mirrors the shrink: the same activation that drops a 4/4 to lethal also turns this flyer into an 8/4 swinging through the air. That symmetry rewards one large activation aimed at a single target over picking off small creatures piecemeal, since every point of toughness you remove becomes a point of evasive damage going the other way. The toughness-only reduction is the restriction doing the balancing work. Because it cannot touch power, it does not defang an attacker's combat damage the way a -X/-X effect would; it kills by reducing toughness to zero, which it can do to an attacker, a blocker, or anything sitting on the other side of the board. The two black pips in the activation cost (not generic mana) anchor it to heavy-black builds, which is where the repeatable, point-by-point assassination earns its keep. It folds a mana sink, a repeatable removal engine, and a self-sufficient finisher into one Vampire that already flies for value, an early example of an activated X-cost ability stapled to a legendary body that closes games on its own.