Splendid Agony

Two -1/-1 counters is a small budget, and the whole spell is built around the freedom to split it. Both counters on one creature push it out of combat or clean off a small threat; one apiece sweeps a pair of x/1 tokens in a single instant. Because the reduction comes from counters rather than a temporary -X/-X debuff, it sticks: a creature shrunk this turn stays shrunk, and a regenerating or indestructible blocker permanently loses the toughness even though it cannot be destroyed outright. Black has printed -1/-1 counter removal across many eras, and this occupies the cheap, instant-speed corner of that lineage, light enough to hold up on the opponent's turn and splittable enough to matter against go-wide boards. The ceiling stays low by design. Two counters does not reach far against anything mid-sized, so this answers small threats or finishes a wounded one rather than dealing with a headline creature on its own. The trade is written plainly in the numbers: a limited counter total buys the right to aim it at one creature or two, at the exact moment you choose.