Sphere of Safety

Oracle Text

Creatures can't attack you or a planeswalker you control unless their controller pays X for each of those creatures, where X is the number of enchantments you control.

Card Rulings

10/1/2012 If you control Sphere of Safety, your opponents can choose not to attack with a creature with an ability that says it attacks if able.
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.