Arrow Pebbles

Layer 1 · Habitat: Descent Wall

A swarm of obsidian insects shaped like arrowheads, 2 to 7 cm long

Description

Insects 2 to 7 cm long, shaped exactly like arrowheads and made entirely of something like obsidian. Alone, one looks like a sharp black stone. They hunt as a swarm: hundreds launch from the cliff at once and strike like a volley of arrows, then settle back into the rock and lie still. Delvers learn to fear a slope of black gravel that is too neat.

Arrow Pebbles

Medium Swarm of Tiny Monstrosities, Unaligned

AC 15 Initiative +4 (14)

HP 36 (8d8)

Speed 10 ft., Fly 60 ft.

Ability scores
STR	DEX	CON	INT	WIS	CHA
3 (−4)	18 (+4)	10 (+0)	1 (−5)	10 (+0)	2 (−4)

Vulnerabilities Bludgeoning

Resistances Piercing, Slashing

Condition Immunities Charmed, Frightened, Grappled, Paralyzed, Petrified, Prone, Restrained, Stunned

Senses Blindsight 30 ft., Passive Perception 10

Languages None

CR 2 (XP 450; PB +2)

Traits

False Appearance. While motionless, the swarm is indistinguishable from a scatter of black gravel.

Swarm. The swarm can occupy another creature's space and vice versa, and it can move through any opening large enough for a Tiny creature. It can't regain Hit Points or gain Temporary Hit Points.

Actions

Volley. Melee Attack Roll: +6, reach 0 ft. Hit: 14 (4d6) Piercing damage, or 7 (2d6) Piercing damage if the swarm has half its Hit Points or fewer.

Arrowstorm (Recharge 5–6). The swarm flies in a 30-foot-long, 5-foot-wide Line and ends its move at the far end. Dexterity Saving Throw: DC 13, each creature in the Line. Failure: 14 (4d6) Piercing damage. Success: Half damage.