Spell Snare

The narrowest counterspell anyone actually plays, and the precision is exactly what earns it a slot. Most counters buy flexibility with mana: pay more, hit anything. This one inverts the trade, charging a single blue mana in exchange for caring about one number on the stack. The constraint reads brutal and plays surgical, because the two-mana slot is where so much of the game's important work happens: the efficient threats, the cheap planeswalkers, the on-curve two-drops decks are built to deploy. A counter that costs less than what it answers is rare, and one that does so while holding up nothing else rewrites the math of an early exchange. The card it can't catch is the card it makes you respect: an opponent who knows you have it will sandbag the two-drop, jam the three instead, and force you to find a different answer, which means the counterspell does work even sitting in hand. That same knife-edge is why it ages with whatever it's pointed at rather than against it. Whether it is live depends entirely on what costs two in a given era, so the card swings from unplayable to nearly mandatory as deckbuilding's center of gravity drifts up and down the curve. Its value is set not by its own text but by the cards it happens to be aimed at.