Flesh Allergy

The two-for-one is the cost; the life loss is the payoff for spending more bodies than you have to. Most edicts and destroy-effects ask you to part with nothing but mana, so the sacrifice clause here looks like a tax until you read the back half: every creature that dies this turn, on either side, feeds the life total drained from your target's controller. That turns a clean kill spell into a settlement. Mass sacrifice outlets, a board wipe earlier in the turn, tokens fed to an altar, a creature that was already dying in combat: each one is a counter on the same ledger, and the controller of the destroyed creature pays for all of it. The design lives in the tension between the two halves. Cast it bare and it is an overpriced removal spell that also costs you a body, a genuinely bad rate. Cast it after the turn has already gotten bloody and the life swing dwarfs the mana you spent. It belongs to the aristocrats lineage of black cards that price death itself, where dead creatures are not a loss but a resource you can spend twice, and it asks you to manufacture a graveyard worth cashing in rather than fire it off the moment you have four lands and a creature to spare.