Winter's Chill

The whole effect runs on a question the caster never gets to answer. As the defender, you set the price and pick the targets; the attacking player then decides, creature by creature, whether to pay nothing and watch it die at end of combat, pay one and keep a neutered body that deals and takes no damage, or pay two and let it swing clean. That two-tier toll is what separates this from a Fog or a kill spell: it taxes a committed alpha strike, bleeding the attacker's open mana while you choose which threats to absorb and which to fund through. The timing is the sharp edge. It resolves only during combat before blockers are declared, so the defender forces the spending decision after the opponent has already committed creatures to the swing, with no chance to redeploy or hold attackers back. The ceiling, though, is chained to the snow-permanent subtheme Ice Age introduced and then mostly walked away from: X can never exceed your snow land count, which ties a flexible instant to a build-around manabase. That dependency is why the card never found a home. The interactive structure is genuinely clever, asking both players to negotiate over a row of attackers in real time, but the resource it scales on never became a thing worth building toward, so the design's reach was always shorter than its idea.