Icy Blast [Khans of Tarkir]

Set: Khans of Tarkir Type: Instant Rarity: Rare Cost: {X}{U} Tap X target creatures.Ferocious — If you control a creature with power 4 or greater, those creatures don't untap during their controllers' next untap steps. "Do not think the sand or the sun will hold back the breath of winter."