Living doll

Living dolls are toys that have been magically animated, typically by a malevolent spirit.

Abilities

 * False Appearance: If the doll is motionless, a creature must succeed on a DC 18 Investigation check to discern that the doll is animate, and at the start of combat the doll has advantage on its initiative roll.
 * Regeneration: Regains 5 hit points at the start of each of its turns unless it takes fire or psychic damage. The doll is destroyed only if it starts its turn with 0 hit points and doesn't regenerate.
 * Grabby Hands: Grapples one opponent, dealing psychic damage at the start of each of its turns.
 * Cackle: Each creature who can hear the marionette's laughter must make a DC 13 Wisdom saving throw. On a failed save, a target takes psychic damage and is incapacitated by a fit of laughter. On a successful save, the target takes half as much damage and is immune to the effect for the next 24 hours. A laughing creature can repeat the save at the end of each of its turns, ending the effect on a success.

History
In the Twilight Mirror Museum, Bells Hells encountered and defeated five living marionettes who guarded a room with one of the exibits of the museum — the Mask of the Mountain from the house of Ovorag in Othanzia.