Multiattack

The flutterflesh makes two bone spur attacks or two tormenting gaze attacks.

Bone Spur

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 17 (2d12 + 4) slashing damage plus 11 (2d10) necrotic damage. If both attacks hit a single creature in the same turn, it is grappled (escape DC 10). As a bonus action, the flutterflesh can choose whether this attack does bludgeoning, piercing, or slashing damage.

Tormenting Gaze

A target creature within 120 feet and able to see the flutterflesh takes 18 (4d8) psychic damage and is paralyzed for 1d4 rounds, or takes half damage and isn't paralyzed with a successful DC 15 Wisdom saving throw. Tormenting gaze can't be used against the same target twice in a single turn.

Slash

Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage. On a critical hit, the target takes an additional 27 (5d10) slashing damage and must make a DC 12 Constitution saving throw. On a failure, the flutterflesh lops off and absorbs one of the target's limbs (chosen randomly) and heals hit points equal to the additional slashing damage it inflicted.