Neogi Hatchling Swarm

The swarm can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

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

Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 22 (6d6 + 1) poison damage, or 11 (3d6 + 1) poison damage if the swarm has half of its hit points or fewer, and the target must succeed on a DC 12 Constitution saving throw or become poisoned for 1 minute. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.