Aurelia (Psychic Spawn)

Regeneration. Aurelia regains 10 hit points at the start of its turn. If Aurelia takes fire or radiant damage, this trait doesn’t function at the start of the Aurelia's next turn. Aurelia's body is destroyed only if it starts its turn with 0 hit points and doesn’t regenerate.

Rejuvenation. When the Aurelia’s body is destroyed, its soul lingers. After 24 hours, the soul creates another body on the same plane of existence and regains all its hit points. While the soul is bodiless, a wish spell can be used to force the soul to go to the afterlife and not return.

Turn Immunity. Aurelia is immune to effects that turn undead.

Vengeful Tracker. The Aurelia knows the distance to and direction of any creature against which it seeks revenge, even if the creature and Aurelia are on different planes of existence. If the creature being tracked by Aurelia dies, She knows.

Multiattack. Aurelia makes two Tekko Kagi attacks.

Tekko Kagi. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage. If the target is a creature against which Aurelia has sworn vengeance, the target takes an extra 14 (4d6) slashing damage. Instead of dealing damage, Aurelia can grapple the target (escape DC 14) provided the target is Large or smaller.

Psychic Assualt. Aurelia targets one creature within 60 feet
of her and assails its mind with Memories of those she has absorbed. The creature must succeed on a DC 14 intelligence saving throw or be stunned until initiative count 20 on the next round.

Teleport. Aurelia magically teleports to an unoccupied space she can see within 40 feet.

Aurelia Has 3 Legendary Actions per turn 

(1 Action)Psychic Assualt. Aurelia targets one creature within 60 feet
of her and assails its mind with Memories of those she has absorbed. The creature must succeed on a DC 14 intelligence saving throw or be stunned until initiative count 20 on the next round.

(1 Action) Absorb Memory. Aurelia Targets 1 creature she can see within 60 feet, That creature must make a DC 14 Charisma Saving throw, On a failed save they take 14 (4d6) Psychic damage and make a single melee attack on the creature closes to them, on a success they take half damage and suffer no further effects.