Season of the Witch | Magic: The Gathering
Formats Season of the Witch is Legal in
Official Oracle Text for Season of the Witch
At the beginning of the end step, destroy all untapped creatures that didn't attack this turn, except for creatures that couldn't attack.
Official Rulings for Season of the Witch
9/20/2013 : A creature won't be destroyed if it was unable to attack that turn, even if you had a way to enable it to attack. For example, a creature that had summoning sickness wouldn't be destroyed even if you had a way to give it haste.