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 dragonfly. The swarm can't regain hit points or gain temporary hit points.

Stings. Melee Weapon Attack: +5 to hit, reach 0 ft., one creature in the swarm's space. Hit:10 (3d4 + 3) piercing damage, or 5 (1d4 + 3) piercing damage if the swarm has half of its hit points or fewer. Additionally, if the swarm is on an Outer Plane, it injects the target with a toxin, the effect of which is determined by the swarm's location:

Upper Plane. The target sheds bright light in a 5-foot radius until the end of its next turn. During that time, the invisible condition has no effect on it.

Neutral Plane. If the target is concentrating on a spell or similar effect, it loses its concentration.

Lower Plane. The target's speed is reduced by 10 feet until the end of its next turn.

Dazzling Lights (Recharge). The swarm shines its lights in a dazzling display. Each creature within 15 feet of the swarm must succeed on a DC 10 Constitution saving throw or have the stunned condition for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Illumination. The swarm sheds bright light in a 15-foot radius and dim light for an additional 15 feet, or it uses a bonus action to extinguish the light.