You are a flying skull, so you can channel your energy to fly 60 ft.

The Demilich emits a bloodcurdling howl. Each creature within 30 feet of the Demilich that can hear the howl must succeed on a DC 15 Constitution saving throw or drop to 0 hit points. On a successful save, the creature is frightened until the end of its next turn. Roll a d6 during a long rest. On a 6,  this ability recharges.

• The demilich targets one creature it can see within 60 feet of it. An antimagic field fills the space of the target, moving with it until initiative count 20 on the next round.

Cloud of Dust. The demilich magically swirls its dusty remains. Each creature within 10 feet of the demilich, including around a corner, must succeed on a DC 15 Constitution saving throw or be blinded until the end of the demilich’s next turn. A creature that succeeds on the saving throw is immune to this effect until the end of the demilich’s next turn.

 charmed, frightened, petrified, prone

You have immunity to psychic; bludgeoning, piercing, and slashing from nonmagical attacks

Bludgeoning, piercing, and slashing from magic weapons

You have Truesight for 60ft.

If the demilich is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

The demilich targets up to three creatures that it can see within 10 feet of it. Each target must succeed on a DC 19 Constitution saving throw or take 21 (6d6) necrotic damage, and the demilich regains hit points equal to the total damage dealt to all targets.

The demilich targets one creature that it can see within 30 feet of it. The target must make a DC 19 Charisma saving throw. On a failed save, the target’s soul is magically trapped inside one of the demilich’s gems. While the soul is trapped, the target’s body and all the equipment it is carrying cease to exist. On a successful save, the target takes 24 (7d6) necrotic damage, and if this damage reduces the target to 0 hit points, its soul is trapped as if it failed the saving throw. A soul trapped in a gem for 24 hours is devoured and ceases to exist.
If the demilich drops to 0 hit points, it is destroyed and turns to powder, leaving behind its gems. Crushing a gem releases any soul trapped within, at which point the target’s body re-forms in an unoccupied space nearest to the gem and in the same state as when it was trapped.