Dark Withering

The hard-cast rate is a deliberate trap: paying six mana for a color-restricted Terror is something no deck would willingly do, and the design knows it. The whole card lives in its madness cost, which collapses that six down to a single black mana the instant you discard it. That turns Dark Withering from an unplayable removal spell into a payoff for a discard engine: a looter, a cycling outlet, a hand-disruption effect that hits your own hand, any way to deliberately ditch a card into the bin at a moment you control. The discard step is the point, not a downside, because it converts a card you'd never cast into instant-speed removal at the price of a Dark Ritual. The nonblack clause is the era-appropriate tax on the rate, narrowing the target to keep it from being a clean catch-all. As a piece of madness design it sits at the extreme end of the mechanic's central tension: a card whose face cost is almost punitively bad precisely so its alternative cost can be aggressively cheap. The math only works if you have an enabler, and that conditional construction is what separates madness payoffs like this from cards that simply have a discount stapled on. Without an outlet it is dead weight; with one, you are killing a creature for one mana at the moment of your choosing.