Crippling Blight

For one black mana, the work here is the can't-block clause, not the stat reduction. The -1/-1 is mostly incidental: it shaves a point and occasionally finishes off an X/1, but the real effect is taking an opponent's defensive creature out of the combat equation entirely. A wall stays on the board, keeps its abilities, and still cannot stop a single attacker. That is the giveaway that this was built for an aggressive shell rather than a controlling one. Control wants the blocker gone permanently and is happy to spend removal on it; aggro just wants the path cleared for the alpha strike, and clearing it for one mana while spending nothing on the threats it actually fears is a favorable trade. Because the Aura lands on an opponent's creature rather than your own, the usual card-disadvantage worry runs backward: if they kill their own neutered blocker to shed the enchantment, that is a one-for-one, and they have spent resources removing a creature you already turned into a liability. The split between a token stat penalty and a hard combat lockout is the tell. This is a tempo tool, not a removal spell, designed to buy turns of unimpeded pressure at the cheapest possible cost rather than to answer a threat for good.