Dark Salvation

The doubled X is the whole arithmetic. Most token-makers scale linearly with mana invested; here the same X that buys the Zombie army also feeds the removal, because the -1/-1 effect counts every Zombie the targeted player controls, not just the ones this spell made. That self-referential loop is the design idea: the bodies you create (plus any already in play) set the size of the debuff, so a single creature takes -1/-1 for each of those Zombies. The "up to one target creature" clause makes the kill optional: in a spot where there is nothing worth shrinking, you make the tokens and skip the removal half. One player both receives the Zombies and supplies the count, which usually means you point the spell at yourself; the trick is that a board you have already populated converts a modest X into a heavy debuff on one creature without spending any more mana this turn. The cost makes the rate punishing early and generous late: at X=3 you are paying six generic and one black for three 2/2s and a single creature shrinking by -3/-3 (more if you arrived with Zombies in play), and the curve only steepens from there. This reads better in a deck already committed to Zombies than as a generic X-spell, since existing tokens inflate the count for free. It is a tribal payoff wearing a flexible tool's clothes, and the deck that wants it was already in the tribe.