Blight Rot

Four -1/-1 counters is a peculiar quantity: enough to erase almost anything that has resolved by the midgame, but delivered as permanent stat reduction rather than destruction. That distinction is the whole design. Against an indestructible threat, or a creature that laughs at the destruction rules through some regeneration-style shield, this does its work regardless, because it never asks whether the creature can be destroyed; it just shrinks the toughness until zero sends the creature away as a state-based action. The counters also linger, so a partial hit (on a large-bodied blocker, or something with more than four toughness) leaves a diminished creature on the board rather than a whiffed spell, and the reduction stacks with any other -1/-1 effects around it. Where a clean kill spell answers the creature and stops, this answers the creature and leaves an anchor for further attrition. The instant speed matters more than the toughness math: it ambushes an attacker or blocker mid-combat, or answers a pump effect by demanding four toughness the creature no longer has. Against noncreature threats it is dead, and against small bodies most of those four counters simply overflow into nothing. It shares black's usual blind spot too: a creature with protection from black cannot be targeted at all, so the counter route buys reach against the destruction-proof, not against the untargetable. That inefficiency is the trade for reach: subtraction-based removal in a color that usually just kills things outright.