Incorporeal Movement. The horror can move through other creatures and objects as if they were difficult terrain. It takes 5 (1d10) force damage if it ends its turn inside an object.

Shadow Stealth. While in dim light or darkness, the horror can take the Hide action as a bonus action.

Shadow Stride. As a bonus action, the horror can step into a shadow within 5 feet of it and magically appear in an unoccupied space within 5 feet of a second shadow that is up to 60 feet away. Both shadows must be cast by a Small or larger creature or object.

Sunlight Sensitivity. While in sunlight, the horror has disadvantage on attack rolls and on Wisdom (Perception) checks that rely on sight.

Multiattack. The horror makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit:21 (4d8 + 3) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit:13 (3d6 + 3) slashing damage, and the target must succeed on a DC 16 Wisdom saving throw or be frightened of the horror until the end of the target's next turn.

Lashing Shadows (Recharge 5–6). Each creature within 60 feet of the horror, except other horrors, must succeed on a DC 16 Dexterity saving throw or take 27 (6d8) necrotic damage.