Encounters: The Upperdark (Underground, Settled)
Swarm, Bat (CR 2)
AC: 16 (+4 size, +2 Dex), touch 14, flat-footed 12
Hit Dice: 3d8 (13 hp)
Fort +3, Ref +7, Will +3
Speed: 5 ft., fly 40 ft. (good)
Space: 10 ft./0 ft.
Base Attack +2; Grapple -
Full Attack: Swarm
Damage: Swarm 1d6
Special Attacks: Distraction, wounding
Climate/Terrain: Temperate desert
Organization: Solitary, flight (2-4 swarms), or colony (11-20 swarms)
Source: Monster Manual
Distraction (Ex): Any living creature that begins its turn with a swarm in its space must succeed on a DC 11 Fortitude save or be nauseated for 1 round. The save DC is Constitution-based.
Wounding (Ex): Any living creature damaged by a bat swarm continues to bleed, losing 1 hit point per round thereafter. Multiple wounds do not result in cumulative bleeding loss. The bleeding can be stopped by a DC 10 Heal check or the application of a cure spell or some other healing magic.
Blindsense (Ex): A bat swarm notices and locates creatures within 20 feet. Opponents still have total concealment against the bat swarm (but swarm attacks ignore concealment).
Skills: A bat swarm has a +4 racial bonus on Listen and Spot checks. These bonuses are lost if its blindsense is negated.
A bat swarm seeks to surround and attack any warm-blooded prey it encounters. The swarm deals 1d6 points of damage to any creature whose space it occupies at the end of its move.