Planar Bestiary
As an undead elemental, an infernal pyre doesn't require air, food, drink, or sleep.
An infernal pyre resembles a large fire elemental whose bright red form contains the burned bones of one or more humanoid creatures. The pyre reeks of burned flesh, and their voice reverberates with the screams of people being roasted alive. They are essentially immaterial (in the way fire is immaterial) undead elemental spirits.
An infernal pyre can form when a particularly evil person is killed by fire or when the body of an especially evil creature is cremated. The damned soul irrevocably corrupts the purity of the fire, creating an entity of rage, hate, and a desire to consume life.
Motive: Hunger to burn living things
Environment: Worlds of the Material Plane, Hell, or dimensions connected to Hell, alone or in groups if several are spawned by burning evil mortals in a mass grave
Health: 15
Damage Inflicted: Moderate wound (5 points)
Armor: 1
Movement: Short
Modifications: Speed defense as level 4 due to large size; stealth as level 2 (due to pyre's bright illumination and sound)
Combat: An infernal pyre attacks twice each round with their fists, inflicting fire damage. If the target is alive or flammable, they ignite. Until the burning victim (or an ally) takes an action to douse the fire, the victim suffers 2 points of damage each round as flame consumes them.
As their action, a pyre can attempt to absorb a burning human-sized or smaller target. While absorbed, the creature is blinded, is only hazily visible from outside, and burns for a moderate wound (5 points) each round (while absorbed, the ignited victim can't be doused). The target can attack from within (but their attacks are hindered by two steps on account of their blindness) or attempt to escape.
An infernal pyre is immune to fire, necrotic, and poison attacks.
Interaction: Infernal pyres know the languages of fire creatures and devils (Ignan and Infernal), but negotiating with them as a living creature is difficult because, from a pyre's point of view, why wait for some promised future reward when living flesh, just calling out to be burned to a crisp, is right in front of them?
Use: A widely hated former ruler dies. At the cremation ceremony, a horrible undead fire being arises.
GM Intrusion: A character breathes in a cloud of choking soot; all they can do on their next turn is violently cough.