Cobbleswarm

Medium Swarm, Unaligned

Armor Class 15 (natural armor)

Hit Points 36 (8d8)

Speed walk +30

Challenge 2

STR
12
+1
DEX
11
+0
CON
11
+0
INT
5
-3
WIS
12
+1
CHA
5
-3

Damage Vulnerabilities False

Damage Resistances bludgeoning, piercing, slashing

Damage Immunities False

Condition Immunities charmed, frightened, grappled, paralyzed, petrified, prone, restrained, stunned

Senses passive Perception 11

Languages —

Special Abilities

False Appearance. While the cobbleswarm remains motionless, it is indistinguishable from normal stones.

Shifting Floor. Whenever the cobbleswarm moves into a creature's space or starts its turn in another creature's space, the creature must succeed on a DC 13 Dexterity saving throw or fall prone. A prone creature must succeed on a DC 13 Dexterity (Acrobatics) check to stand up in a space occupied by the swarm.

Swarm. The cobbleswarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a Tiny stone. The swarm can't regain hp or gain temporary hp.

Actions

Stings. Melee Weapon Attack: +3 to hit, reach 0 ft., one target in the swarm's space. Hit: 15 (6d4) piercing damage, or 7 (3d4) piercing damage if the swarm has half its hp or fewer.

Bonus Actions

Shift and Tumble. The cobbleswarm pushes a prone creature in its space up to 5 feet away from it.

Source: Tome of Beasts 2023 · OGL/Open