Minor Misstep

Spell Pierce built a whole subgenre out of the idea that a one-mana counter does not need to hit everything; it needs to hit the right things cheaply. This one narrows the filter differently. Instead of naming a permanent type, it keys on mana value, answering only the cheapest layer of the game: the mana dorks, the one-drop threats, the fetchable enablers, the cantrips and rituals that let combo decks start their turn. The floor on that restriction is the interesting design work. A counterspell that can only stop spells costing one or less is dead weight against most of a control mirror, but it is a hard wall against the openings that swing games in the first two turns. It also folds back on itself: it counters itself, it counters Spell Pierce, it counters Fatal Push, it counters the fast mana that powers a turn-one play, which makes it a pressure valve on the very earliest exchanges. The lineage here runs through Mental Misstep, the free-cost version that proved so warping it was chased out of every eternal format that would have it. This is the same targeting logic priced honestly at a mana, trading the broken free cost for a spell that has to fit inside your own opening curve. The restriction is not a weakness bolted on; it is the entire premise.