Swarm of Bats

Medium swarm of Tiny beasts, unaligned

Armor Class: 12
Hit Points: 22 (5d8)
Speed: 0 ft., fly 30 ft.

STR: 5 (−3)
DEX: 15 (+2)
CON: 10 (+0)
INT: 2 (−4)
WIS: 12 (+1)
CHA: 4 (−3)

Damage Resistances: bludgeoning, piercing, slashing
Condition Immunities: charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses: blindsight 60 ft., passive Perception 11
Languages: —
Challenge: 1/4 (50 XP)

Echolocation. The swarm can't use its blindsight while deafened.

Keen Hearing. The swarm has advantage on Wisdom (Perception) checks that rely on hearing.

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

Actions

Bites. Melee Weapon Attack: +4 to hit, reach 0 ft., one creature in the swarm's space. Hit: 5 (2d4) piercing damage, or 2 (1d4) piercing damage if the swarm has half of its hit points or fewer.

Running this fight? Add the swarm of bats to the initiative tracker: type its name and the AC, hit points and initiative bonus fill in, and the book button shows this stat block mid-fight.