Medium Beast (Swarm), unaligned
Armor Class 13
Hit Points 54 (12d8)
Speed fly +30, swim +30, walk +10
Challenge 2
Damage Resistances bludgeoning, piercing, slashing
Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned
Senses darkvision 60 ft., passive Perception 11
Languages —
Amphibious. The swarm can breathe air and water.
Keen Smell. The swarm has advantage on Wisdom (Perception) checks that rely on smell.
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 esteron. The swarm can't regain hit points or gain temporary hit points.
Bites. Melee Weapon Attack: +5 to hit, reach 0 ft., one creature in the swarm's space. Hit: 14 (4d6) piercing damage, or 7 (2d6) piercing damage if the swarm has half its hp or fewer.
Source: Tome of Beasts 2 · OGL/Open