Sphere of Safety
Enchantment
Creatures can't attack you or planeswalkers you control unless their controller pays 
for each of those creatures, where X is the number of enchantments you control.
Slawomir Maniak
Pioneer Masters (PIO)
• #34Rulings
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.
(wotc • 2012-10-01)
Rulings
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.
(wotc • 2012-10-01)