Imprison | Magic: The Gathering
Formats Imprison is Legal in
Official Oracle Text for Imprison
Whenever a player activates an ability of enchanted creature with in its activation cost that isn't a mana ability, you may pay . If you do, counter that ability. If you don't, destroy Imprison.
Whenever enchanted creature attacks or blocks, you may pay . If you do, tap the creature, remove it from combat, and creatures it was blocking that had become blocked by only that creature this combat become unblocked. If you don't, destroy Imprison.
Official Rulings for Imprison
4/15/2013 : A mana ability is an ability that (1) isn't a loyalty ability, (2) doesn't target, and (3) could put mana into a player's mana pool when it resolves.