Boon of Death’s Grace (5e Epic Boon)

Death itself has deemed you worthy of its power, granting you the power to keep the dead as they should be. You gain the following benefits:

As an action, you may kill an undead creature that is charmed or frightened of you instantly, causing them to disintegrate to dust.
The first time an undead creature sees you, they must attempt a DC 8 + your proficiency bonus + your wisdom modifier Intelligence saving throw. On a failure, the strengthened pull of the afterlife weakens them, causing them to become charmed or frightened of you while they can see you. If they are immune to both conditions, you deal an additional 2d12 necrotic damage to them from all sources while they can see you.
You gain immunity to necrotic and poison damage, and the poisoned, charmed, and paralyzed conditions.
Whenever you take necrotic damage, you take no damage and are instead healed for the same amount of damage.