Medium Beast
Armor Class 12
Hit Points 18 (4d8)
Speed fly +30, walk +5
Challenge 1/4
Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned, unconscious
Senses blindsight 60 ft., passive Perception 11
Echolocation. The swarm can't use blindsight while deafened.
Keen Hearing. The swarm has advantage on Perception checks that rely on hearing.
Swarm. The swarm can occupy another creatures space and move through any opening large enough for a Tiny creature. It can't gain hit points or temporary hit points.
Bites. Melee Weapon Attack: +4 to hit, reach 0 ft., one target. Hit: 7 (2d6) piercing damage or 3 (1d6) piercing damage if the swarm is bloodied.
Source: Level Up Advanced 5e Monstrous Menagerie · OGL/Open