Winter's Chill

Cast only during combat before defense is chosen. At end of combat, destroy X target attacking creatures; X cannot be greater than the number of snow-covered lands you control. For each attacking creature, its controller may pay 1 or 2 to prevent it from being destroyed in this way. If that player pays 1, the creature neither deals nor receives damage in combat. If that player pays 2, the creature deals and receives damage in combat as normal.