Krosa | Magic: The Gathering
Formats Krosa is Legal in
Official Oracle Text for Krosa
Whenever you roll , you may add to your mana pool.
Official Rulings for Krosa
10/1/2009 : A face-up plane card that's turned face down becomes a new object with no relation to its previous existence. In particular, it loses all counters it may have had.
10/1/2009 : The controller of a face-up plane card is the player designated as the "planar controller." Normally, the planar controller is whoever the active player is. However, if the current planar controller would leave the game, instead the next player in turn order that wouldn't leave the game becomes the planar controller, then the old planar controller leaves the game. The new planar controller retains that designation until he or she leaves the game or a different player becomes the active player, whichever comes first.
10/1/2009 : If an ability of a plane refers to "you," it's referring to whoever the plane's controller is at the time, not to the player that started the game with that plane card in his or her deck. Many abilities of plane cards affect all players, while many others affect only the planar controller, so read each ability carefully.