Encounters: Anauroch - Plain of Standing Stone (Day)

Swarm, Locust (CR 3)

Diminutive Vermin (Swarm)
Alignment: Always neutral
Initiative: +4 (Dex); Senses: darkvision 60 ft., Listen +4, and Spot +4

AC: 18 (+4 size, +4 Dex), touch 18, flat-footed 14
Hit Dice: 6d8-6 (21 hp)
Fort +4, Ref +6, Will +2

Speed: 10 ft., fly 30 ft. (poor)
Space: 10 ft./0 ft.
Base Attack +3; Grapple -
Attack: Swarm
Full Attack: Swarm
Damage: Swarm 2d6
Special Attacks: Distraction

Abilities: Str 1, Dex 19, Con 8, Int -, Wis 10, Cha 2
Special Qualities: immune to weapon damage, swarm, vermin
Feats: -
Skills: Listen +4 and Spot +4
Advancement: -

Climate/Terrain: Temperate Planes
Organization: Solitary, cloud (2-4 swarms), or plague (11-20 swarms)
Treasure: None

Source: Monster Manual

Distraction (Ex): Any living creature that begins its turn with a locust swarm in its space must succeed on a DC 12 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.

Skills: A locust swarm has a +4 racial bonus on listen and Spot checks.

A locust swarm surrounds and attacks any living prey it encounters. The swarm deals 2d6 points of damage to any creature whose space it occupies at the end of its move.

Faerûnian Random Encounters by Region and Locale