False Appearance.

If the swarm is motionless at the start of combat, it has advantage on its initiative roll. Moreover, if a creature hasn't observed the swarm move or act, that creature must succeed on a DC 18 Intelligence (Investigation) check to discern that the swarm is animate.

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

Actions

Swarm of Bites.

Melee Weapon Attack: +5 to hit, reach 0 ft., one creature in the swarm's space. Hit: 13 (3d6 + 3) piercing damage, or 6 (1d6 + 3) piercing damage if the swarm is at half of its hit points or fewer, and the target has disadvantage on attack rolls until the start of its next turn.

Bonus Actions

Scale Dust (1/Day).

The swarm releases magical glittering dust from its wings. Each creature within 10 feet of the swarm must succeed on a DC 13 Dexterity saving throw or be outlined in blue light for 10 minutes. While outlined in this way, a creature sheds dim light in a 10-foot radius and can't benefit from being invisible. In addition, every Dragon within 1 mile of the creature becomes aware of it and can unerringly track the creature. Casting dispel magic on the creature ends the effect on it.

Swarm of Hoard Scarabs