Nyctli Swarm

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny nyctli. The swarm can't regain hp or gain temporary hp.

Innate Spellcasting (1/Day). The nyctli swarm can innately cast fear, requiring no material components. Its innate spellcasting ability is Charisma.

Stingers. Melee Weapon Attack: +8 to hit, reach 0 ft., one target in the swarm's space. Hit: 21 (6d6) piercing damage, or 10 (3d6) piercing damage if the swarm has half of its hp or fewer. The target must make a DC 16 Constitution saving throw. On a failure, a creature takes 42 (12d6) necrotic damage and is blinded for 1 minute. On a success, a creature takes half the damage and isn't blinded. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Douse Light. As the nyctli, except the swarm can't dispel light created by a spell of 6th level or higher.