Darkblast

A single black mana buys a -1/-1, which kills a mana dork, shrinks a blocker, or finishes off something already wounded. On the surface that is a modest, narrow effect. The reason it earned a slot is that it never stays in the graveyard: dredge 3 lets you skip a draw step to mill three cards and return Darkblast to hand, where it costs the same black mana to cast all over again. The numbers are small but the supply is endless, and against a board of one-toughness threats a repeatable single-target ping becomes its own kind of grind. The trade is honest in both directions. The draw you forgo and the three cards you mill are the price of getting the spell back, so the loop that picks off the bottom of an opponent's curve is the same loop steadily emptying your library. That second cost made it a graveyard-deck tool as much as a removal spell: decks that wanted the mill could run it purely as a recurring dredge engine, treating the -1/-1 as a bonus rather than the point. Instant speed sharpens the small numbers, letting you answer a pump spell mid-combat or drop a blocker below lethal at the last moment, then dredge the card back next turn instead of drawing fresh. Few designs state dredge's central bargain this plainly: a low-rate effect made infinitely repeatable, paid for in draws and in the depth of your own deck.