Ankhou

Damage Transfer. While attached to a creature's shadow, the ankhou takes only half the damage dealt to it (rounded down), and that creature takes the other half.

Shadow Teleport. While the ankhou remains within an object or a creature's shadow, it can teleport itself and one Medium or smaller size creature or object to another dim or dark location within 200 feet. 

Light Sensitivity. While in bright light, the ankhou has disadvantage on attack rolls and Wisdom (Perception) checks that rely on sight.

Shadowfell’s Sight. Magical darkness doesn’t impede the ankhou’s darkvision.

Amorphous. The ankhou can move through a space as narrow as 1 inch wide without squeezing.

Unusual Nature. The ankhou doesn t require air, food, drink, or sleep.

Spellcasting. The ankhou is a 14th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17). It has the following spells and cast them without any material components.

3/day: darkness, 

1/ day: maddening darkness, 

Multiattack. The ankhou makes three attacks: one with its bite and two with its tails.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one creature. Hit: 13 (2d6 + 6) piercing damage, and if the target is Large or smaller, the ankhou attaches to the target's shadow, and the target is restrained and unable to move while the ankhou is attached. While attached, the ankhou can control the target's movement or deal 10d4 psychic damage and the ankhou regains hit points equal to that amount. A humanoid slained by this will rise as a shadow in the next turn. An attached ankhou can be expelled by a bright light.

Tail. Melee Weapon Attack: +10 to hit, reach 10 ft., one creature. Hit: 10 (1d8 + 6) slashing damage.

Mind Whisper. Each creature within 20 feet of the ankhou that can hear its whisper and that isn't a fey must succeed on a DC 16 Intelligence saving throw or become paralyzed until the end of the ankhou's next turn. If a creature's saving throw is successful, the creature is immune to the ankhou's whisper for the next 24 hours.

Duplicate (1/day). As a bonus action, the ankhou can create up to four duplicates. The duplicates are similar to the ankhou but they only have 40 HP, they are unable to use Mind Whisper and cast any spells. They move after the ankhou's turn.

If the duplicates are alive for 44 days, they will become true ankhou with all of its abilities, spells and HP.