Riot Control | Magic: The Gathering
Formats Riot Control is Legal in
Official Oracle Text for Riot Control
Official Rulings for Riot Control
4/15/2013 : If a source an opponent controls would deal noncombat damage to you, you may choose to have Riot Control prevent that damage before that opponent may choose to redirect that damage to a planeswalker you control.
4/15/2013 : Riot Control doesn't prevent combat damage that would be dealt to planeswalkers you control by creatures attacking them. It also doesn't prevent damage that would be dealt to creatures you control.