Wrack with Madness

Removal that prices a creature by its own offense: the target deals damage to itself equal to its power, so the spell kills anything whose power meets or exceeds its toughness. That covers most creatures worth killing, including the glass-cannon attackers that carry more power than they can absorb, while the genuine survivors are the lopsided defensive bodies (walls, blockers with toughness far above their power) and anything sitting at zero power, which takes no damage at all. That inverts the usual red calculus, where burn is priced against toughness; here a fragile beater with a fat power number is the easy kill and a 0/4 is untouchable. The flavor follows the math cleanly: the creature's own strength becomes the murder weapon, a small family of red removal built on turning offense into self-destruction. Because the damage is dealt by the creature to itself rather than by the red spell, it dodges prevention effects that apply only to damage from the red spell itself, though it still targets like any other red spell and cannot be aimed at a creature with protection from red in the first place. The sorcery speed and four mana keep it deliberate: this answers a board state on your own turn, not an attacker mid-combat, so its best work is peeling a resolved threat off the table rather than ambushing one.