Monster

Swarm of Centipedes

Medium swarm of Tiny beasts, unaligned

Armor Class: 12 (natural armor)
Hit Points: 22 (5d8)
Speed: 20 ft., climb 20 ft.

STR: 3 (-4)
DEX: 13 (+1)
CON: 10 (+0)
INT: 1 (-5)
WIS: 7 (-2)
CHA: 1 (-5)

Damage Resistances: bludgeoning, piercing, slashing
Condition Immunities: charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses: blindsight 10 ft., passive Perception 8
Languages: None
Challenge: 1/2 (100 XP)
Proficiency Bonus: +2

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

Actions

Bites. Melee Weapon Attack: +3 to hit, reach 0 ft., one target in the swarm's space. Hit: 10 (4d4) piercing damage, or 5 (2d4) piercing damage if the swarm has half of its hit points or fewer. A creature reduced to 0 hit points by a swarm of centipedes is stable but poisoned for 1 hour, even after regaining hit points, and paralyzed while poisoned in this way.