Shinen-Gaki (CR 4)

Medium Undead (Fire and Spirit)
Alignment: Always chaotic evil
Initiative: +2 (Dex); Senses: Listen +7 and Spot +7
Languages: usually Common

AC: 20 (+2 Dex, +8 natural), touch 12, flat-footed 18
Hit Dice: 4d12 (26 hp); DR: 5/honorable
Fort +1, Ref +3, Will +5
Speed: Fly 40 ft. (average)
Space: 5 ft./5 ft.
Base Attack +2; Grapple -3
Attack: Tendril +4 melee
Full Attack: Tendril +4 melee
Damage: Tendril 1d6 and 1d6 fire
Special Attacks/Actions: Burn
Abilities: Str 10, Dex 14, Con -, Int 8, Wis 13, Cha 12
Special Qualities: undead, fast healing 4, fire subtype, gaki qualities
Feats: Alertness; Weapon Finesse
Skills: Intimidate +5, Listen +7, Search +4, Sense Motive +5, and Spot +7
Advancement: 5-12 HD (Medium-size)
Climate/Terrain: Any land
Organization: Solitary or band (2-4)
Treasure: None

Source: Oriental Adventures

Gaki are minor undead spirits, the spirits of wicked mortals who return to the world of the living in the form of horrible monsters as punishment for their sins.

Often created from the spirit of a traitorous or cowardly soldier, a shinen-gaki is the spirit of a wicked humanoid. It resembles a hovering ball of flame, usually bright red, blue, white, or yellow. A dark spot near the center of the fiery ball's surface serves as its eyes, but no other features distinguish it. The gaki burns and consumes any living creature it encounters.

All gaki speak the languages they knew in life (at least Common). With the exception of the jiki-ketsu-gaki, however, they generally communicate only in grunts and moans.

Fire Subtype

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.

Spirit Subtype

Spirit creatures include some fey and elementals (nature spirits), outsiders (celestial spirits), undead (ghosts and ancestors), and even dragons. Spirit creatures are nor necessarily incorporeal, despite their name - in the worlds of Oriental Adventures, some spirits are as much flesh and bone as humans are. The only game effect of the spirit type modifier is that spirit creatures are all affected by spells such as commune with greater spirit, invisibility to spirits, and protection from spirits.