Mask of Avacyn
Artifact — Equipment
Equipped creature gets +1/+2 and has hexproof. (It can't be the target of spells or abilities your opponents control.)
Equip 
It hides the face and protects the soul.
James Paick
Commander Legends (CMR)
• #466Rulings
If Mask of Avacyn somehow becomes attached to a creature an opponent controls, that creature can't be the target of spells or abilities you control.
(wotc • 2011-09-22)
Rulings
If Mask of Avacyn somehow becomes attached to a creature an opponent controls, that creature can't be the target of spells or abilities you control.
(wotc • 2011-09-22)