Gisela, Blade of Goldnight | Magic: The Gathering
Formats Gisela, Blade of Goldnight is Legal in
Official Oracle Text for Gisela, Blade of Goldnight
If a source would deal damage to an opponent or a permanent an opponent controls, that source deals double that damage to that player or permanent instead.
If a source would deal damage to you or a permanent you control, prevent half that damage, rounded up.
Official Rulings for Gisela, Blade of Goldnight
5/1/2012 : If multiple replacement effects would modify how damage would be dealt, the player being dealt damage (or the controller of the permanent being dealt damage) chooses the order in which to apply those effects.
5/1/2012 : If damage dealt by a source you control is being divided among multiple permanents an opponent controls or among an opponent and one or more permanents he or she controls simultaneously, divide the original amount and double the results. For example, if you attack with a 5/5 creature with trample and your opponent blocks with a 2/2 creature, you can assign 2 damage to the blocker and 3 damage to the defending player. These amounts are then doubled to 4 and 6 damage, respectively. You can't double the damage to 10 first and then assign 2 to the creature and 8 to the player.