Ice Age

Kicker {w/u}{w/u} (You may pay an additional {w/u}{w/u} as you cast this spell.)
Destroy all tapped creatures, then, if Ice Age was kicked, tap all creatures. They don't untap during their controller's untap steps.
Rebound (If you cast this spell from your hand, exile it as it resolves. At the beginning of your next upkeep, you may cast this card from exile without paying its mana cost.)