Kiku's Shadow

Removal that turns a creature's own strength against it, but the math is fussier than the conceit suggests. Because the creature deals itself damage equal to its power, it only dies when that power meets or exceeds its toughness: a 4/4 falls, a 5/5 falls, but a 2/3 shrugs off two damage and a 4/5 walks away bruised. That calibrates the spell for a precise quarry, the aggressively statted attacker whose power outruns its body, the kind of fat undefended finisher that defensive black removal usually has to overpay to answer. A 0-power creature deals itself nothing and survives untouched, but the more telling blind spot is every well-rounded body whose toughness simply outpaces its power. The damage being self-inflicted is more constraint than loophole: the creature is the source, so its controller cannot redirect prevention onto the spell, but a creature with protection from its own color prevents the self-damage entirely, and an indestructible body takes the hit and lives. The other limits are the ordinary ones for a black spell that targets: hexproof or shroud puts the creature out of reach, and protection from black stops it from ever resolving on its target. Charging a flat two mana whether the threat is a 3/3 or a 9/2 inverts the usual removal curve, paying the same price against a creature whose own aggression is its undoing. Narrow, then, and toothless against grindy midrange bodies, but exact against the threat it was built to punish.