Hellfire

Black wraths are supposed to cost something the color does not freely give, and Legends found the most direct currency available: the player's life total, scaled to the size of the wrath itself. The damage clause is the design's whole argument. A symmetrical board sweep would be too clean for a color that historically pays in flesh, so the cost grows with the payoff. Clear two creatures and you take five; clear six and you take nine; clear a stalled midrange board and the spell can kill its caster outright. The "nonblack" rider does the rest of the bargaining, leaving a window for a mono-black deck to wrath asymmetrically at the cost of bleeding for it, which is the same trade Damnation would later offer at a flat rate and which every black sweeper since has tried to price more gently. What keeps Hellfire a curiosity rather than a playable answer is that the rate moves the wrong direction: the better the spell performs, the more it hurts you, so the ceiling and the floor are inverted from how modern sweepers are tuned. It belongs to the early era when black's access to mass removal was treated as a genuine color-pie transgression, payable only in increments of self-immolation.