Boogeyman

Telepathy. The boogeyman can telepathically communicate with a creature it can see within 100 ft. When it does so, the targeted creature may respond, even if it doesn’t see the boogeyman.

Psychic Leech. At the start of each of the boogeyman’s turns, each creature within 5 feet of it must succeed on a DC 12 Wisdom saving throw or take 10 (3d6) psychic damage.

Mimicry. The boogeyman imitates small sounds and words it has heard, in any language. A creature who hears it can make a DC 18 Wisdom (Insight) check to discern the sounds are imitations.

Magic Weapons. The boogeyman's weapon attacks are magical.

 Fear Incarnate. The boogeyman can cast fear as a cantrip.

Spellcasting. The boogeyman is a fourth-level spellcaster. Its spellcasting ability is charisma (spell save DC 15, + 9 to hit with spell attacks). The boogeyman has following spells prepared:
Cantrips (at will): Minor Illusion, Mind Sliver 

1st level (4 slots): Disguise Self, Inflict Wounds, Hideous Laughter, Bane, Hex

 2nd level (3 slots): Blindness/Deafness, Invisibility, Suggestion, Tasha's Mind Whip

3rd level (3 slots): Bestow Curse, Major Image, Vampiric Touch (deals psychic damage)

4th level (2 slots): Greater Invisibility, Hallucinatory Terrain

Multiattack. The boogeyman makes 2 attacks.

Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 13 (3d6 + 3) slashing damage.

Pierce. Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 13 (2d8 + 4) piercing damage.

Dreadful Bite (Recharge 2). Melee Weapon Attack: +5 to hit, reach 5 ft., 1 target. Hit: 6 (1d8 + 2) piercing damage + 5 (2d4) psychic damage.

Frightful Glare (Recharge 4). The boogeyman targets one creature it can see within 10 feet of it. The target must make a DC 15 wisdom saving throw against this magic. On a failed save, the target becomes frightened.