Hydrosurge

The -X/-0 line is an old blue idiom for a very specific job: cap a creature's damage output without killing it, so the toughness stays intact and the body lives to fight on. At a five-point swing for one mana, the obvious use is defensive, neutering an incoming attacker by stripping enough power to make a lethal swing harmless for one combat step. But the effect cuts both ways at the table. Cast on a blocker, the same -5/-0 can save your attacker from dying in combat, since the blocker now deals far less damage than its printed power suggests. That dual application sets it apart from Fog, which blanks all combat damage at once but answers no single threat repeatedly and never picks its target. This trades breadth for precision: you choose the one creature that matters and shut its offense off, leaving the rest of the board to other answers. The catch is the permanence of the target. The creature you point this at is still standing when the turn ends, so you have spent a card to survive or win one exchange while the threat remains a problem next turn. That is why this style of damage suppression has always lived at the margins of constructed play, earning its keep as a clean, cheap response to the single largest body on the other side rather than as a reusable engine or a source of card advantage.