Sphere of Safety | Magic: The Gathering
Formats Sphere of Safety is Legal in
Official Oracle Text for Sphere of Safety
Official Rulings for Sphere of Safety
10/1/2012 : In a Two-Headed Giant game, if one player controls Sphere of Safety, creatures can't attack that player's team or a planeswalker that player controls unless their controller pays for each of those creatures he or she controls. Creatures can attack planeswalkers controlled by that player's teammate without having to pay this cost.