Fire Bat (CR 3)
AC: 16 (+1 size, +3 Dex, +2 natural), touch 14, flat-footed 13
Hit Dice: 6d8-6 (21 hp)
Fort +1, Ref +8, Will +0
Speed: 10 ft., fly 50 ft. (good)
Space: 5 ft./5 ft.
Base Attack +4; Grapple -1
Attack: Bite +8 melee
Full Attack: Bite +8 melee
Damage: Bite 1d6-1 plus 1d6 fire
Special Attacks/Actions: Attach, burn, devour
Abilities: Str 8, Dex 17, Con 8, Int 6, Wis 7, Cha 5
Special Qualities: elemental traits, fire subtype, regeneration 5
Feats: Flyby Attack; Weapon Finesse (bite) (B)
Skills: Hide +15, Listen +9, and Spot +9
Advancement: 7-12 HD (Small); 13-18 HD (Medium-size)
Climate/Terrain: Elemental Plane of Fire or volcanoes
Organization: Solitary or swarm (11-20)
Monster Manual II
Attach (Ex): If a fire bat hits with its bite attack, it latches onto the opponent's body. An attached fire bat is effectively grappling its prey. The fire bat loses its Dexterity bonus to AC (giving it an AC of 13) but holds on with great tenacity, dealing 1d6 points of fire damage each round it remains attached. An attached fire bat can be struck with a weapon or grappled itself. To remove an attached fire bat through grappling, the opponent must achieve a pin (see Grapple) against the fire bat. Each grapple attempt subjects the opponent to the fire bat's burn attack.
Burn (Ex): Any creature that is hit by a fire bat's bite attack (or that hits the fire bat with a natural weapon or an unarmed attack) must succeed at a Reflex save (DC 12) or catch fire (see Catching on Fire). The fire burns for 1d4 rounds. Immersing a fire bat in at least 10 gallons of water extinguishes its flames and prevents it from flying but does not otherwise harm the creature. The fire bat's flames reignite after 10 rounds.
Devour (Ex): Once it is attached, a fire bat devours the opponent's flesh, automatically dealing 1d6-1 points of bite damage and 1d6 points of fire damage each round it remains attached. After dealing 6 points of damage, the fire bat is sated; on the next round it detaches and flies away to digest the meal.
Blindsight (Ex): A fire bat emits high-frequency sounds, inaudible to most other creatures, that bounce off nearby objects and creatures. This ability enables it to discern objects and creatures within 120 feet. The fire bat usually does not need to make Spot or Listen checks to notice creatures within range of its blindsight. A silence spell negates this ability and forces the fire bat to rely on its weak vision (which has a maximum range of 10 feet).
Fire Subtype (Ex): A fire bat is immune to fire damage but takes double damage from cold unless a saving throw for half damage is allowed. In that case, the creature takes half damage on a success and double damage on a failure.
Regeneration (Ex): Cold attacks deal normal damage to a fire bat.
Skills: A fire bat receives a +4 racial bonus on Spot and Listen checks. These bonuses are lost if its blindsight is negated.
In combat, fire bats display a level of cunning that belies their limited intelligence, dividing their attacks evenly among all the possible targets. Once a fire bat is sated (see devour), it breaks off and leaves the fight. When one-fourth of the swarm is sated or slain, all the remaining fire bats break off and flee, only to shadow their prey and attack again when the time is right. They repeat this pattern until the whole swarm has fed.
A creature with the fire subtype has immunity to fire. It has vulnerability to cold, which means it takes half again as much (+50%) damage as normal from cold, regardless of whether a saving throw is allowed, or if the save is a success or failure.