Liliana's Dark Oath

If your devotion to black is more than 4, Liliana's dark oath is a 6/5 legendary enchantment creature called, Liliana of the dark oaths with target ability target creature that is or was on the battlefield.
Opponents can't cast spells called Liliana's dark oath as long as you control a creature called Liliana of the dark oaths.
An oath of death, not of protection.