Mutual Destruction

A single black mana buys unconditional creature destruction, no restriction on color or type, which is a rate black rarely gets to touch. The additional cost pays for it directly: you sacrifice a creature to cast it, so the spell reads as a one-for-one that becomes a two-for-one against you whenever the fodder had value of its own. That constraint steers it into aristocrats and sacrifice shells, where the creature you give up was already headed for the graveyard to fuel a death trigger or an engine payoff. The flash clause is the wrinkle worth reading twice: the spell has no innate flash, but grants itself instant-speed timing the moment you control any permanent with flash, so a single ambush body elsewhere on the board converts a sorcery-speed removal spell into a combat trick and an end-step interaction piece. That conditional-flash template is unusual: rather than pricing instant speed into the card directly, it outsources the timing to a deckbuilding commitment, rewarding a board already built around flash without gifting the flexibility to a deck that isn't. The result is a removal spell whose ceiling depends less on the target it kills and more on the two permanents you already control when you cast it.