Toxic Stench

Threshold rewrites this card mid-game from a marginal shrink effect into a clean kill. Early, the same two mana nudges a creature down a single point, enough to finish off something in combat or pick off an X/1, and not much else. Once seven cards have piled into your graveyard, the spell instead destroys that creature outright with no regeneration, which is the rate a black removal spell wants to be paying. That swing is the entire design: the threshold mechanic of this era upgraded the spell you were casting right now based on how full your yard had grown, and few cards demonstrate the idea more cleanly, since the floor is playable and the ceiling is premium. The nonblack clause is the quiet limiter that survives in both modes; black creatures are never legal targets at all, so threshold cannot turn this into a universal answer, only a strong conditional one. The structure asks a deckbuilding question rather than a sequencing one: fill the yard fast and you have a discounted instant-speed kill spell for everything outside your own color, but stumble on enabling it and you are holding a conditional combat poke. It is the threshold pattern in miniature, a single spell that is two different cards depending on which half of the game you cast it in.