Zerthul

Zerthul are born in shallow rivulets of brimstone where lesser pit-forges bubble; they are not summoned so much as coaxed into existence by careless fire-magic and desperate bargains. Folklore says a flare of anger from a fire-witch pooled into a small, thinking thing that learned to mimic speech and the pleasures of heat. In the Abyss they are scorned as nuisances, but on the Material Plane they can cause devastating campfires and ruin delicate rituals. Travelers tell of the Ashward Circle, a band of hedge-mages and charcoal-workers who keep handwritten registries of small demonic encounters. Their records describe Zerthul as solitary, preferring to haunt hearths and forges rather than the bloodier haunts of greater fiends. They feed on stray embers and the scent of fear, lairing in chimneys, coal-pits, and ruined braziers. Scholars such as Master Renvik of Nightford have argued Zerthul are useful barometers of infernal influence — where Zerthul appears, greater demonic attention often follows.

Zerthul is roughly the size of a large housecat (about 2–3 feet long from snout to tail). Its skin is a mottled mix of scorched umber and raw, flesh-pink tissue; veins of cooled slag crisscross its flanks. The wings are thin, membranous, and fleshy like the inside of a mouth, veined with glowing ember-lines that pulse when it exerts itself. Its eyes are beadlike and blood-red, set in a narrow face framed by a row of tiny, broken horns. A short, whip-like tail ends in a puckered, ember-smoke vent. Its limbs end in grasping hands and footpads with tiny, blackened claws that leave smudges of ash on anything it touches. Steam and tiny sparks sometimes leak from the seams where its wings attach.