Fyrefly (CR 1/8)

Fine Magical Beast
Alignment: Usually chaotic neutral
Initiative: +7; Senses: darkvision 60 ft., low-light vision, Listen +4, and Spot +4

AC: 25 (+8 size, +7 Dex), touch 25, flat-footed 18
Hit Dice: 1/2d10-1 (1 hp)
Fort +1, Ref +8, Will +1
Speed: Fly 50 ft. (perfect)
Space: 1 ft./0 ft.
Base Attack +1; Grapple -20
Attack: Touch +4 melee
Full Attack: Touch +4 melee touch
Damage: 1 fire plus combustion
Special Attacks/Actions: Combustion
Abilities: Str 1, Dex 25, Con 8, Int 9, Wis 12, Cha 13
Special Qualities: immunity to fire, partial immunity to cold, vulnerability to water
Feats: Alertness
Skills: Hide +23, Listen +4, Move Silently +9, and Spot +4
Advancement: -
Climate/Terrain: Warm and temperate forest
Organization: Solitary
Treasure/Possessions: None

Source: Converted

Combustion (Ex): Anyone a fyrefly touches must succeed on a DC 10 Reflex save or take an extra 1d6 points of fire damage as clothes ignite or armor becomes searing hot. The damage continues for another 1d3 rounds after the fyrefly's last successful attack. Fyreflies can also ignite flammable materials with a touch. The save DC is Constitution-based.

Partial Immunity to Cold (Ex): The fyrefly is partially immune to cold damage. Each time it would normally take damage from a cold attack, it takes no damage but instead falls into a catatonic coma for 24 hours. During this time, it cannot be awakened by any means. This is not a sleep effect.

Vulnerability to Water (Ex): Contact with water or a spell with the water descriptor has the same effect as its partial immunity to cold, except the fyrefly is allowed a DC 10 (or 10 + spell level) Fortitude save to negate the effect.

The adult fyrefly is not aggressive in the least. When it comes into contact with anything flammable, it sets objects ablaze, and it can use this ability to defend itself.