Larva

Larvae, also called soul larvae, were what remained of the souls of mortals corrupted by evil that were unclaimed by fiends via contract or otherwise. They were trapped in the Shadowfell or Hades to be captured by predators such as night hags, rakshasas or liches in order to be consumed or sold.

Living mortals could also be transformed into larvae by prolonged exposure to the plane of Hades.

Description
Soul larvae were long, yellow, worm-like monsters whose squirming bodies appeared both sickly and fat. They oozed an odorous, viscous slime from their bodies that coated the ground they wriggled across like a slug's trail, producing a noise like a vomiting dog as they moved. The actual body of a soul larva was fluid, almost liquid in texture, and the foul stench of their sticky secretions never seemed to fade. Rather than the head of a worm, soul larva had a much more disturbing feature, a grotesquely disformed head with facial features reminiscent of their former mortal form.

Behavior
Soul larvae were wretched, miserable creatures stripped of the intelligence and personality they had in life apart from faint, leftover recollections. Despite their greatly reduced mental faculties they could still understand the languages they knew in life, and scholars that studied them believed them to possess their own crude but indecipherable language of instinctual body motions.

Those in the Gray Wastes were generally lacking in ambition, typically lying down in the emotionless wasteland in massive piles, barely moving, if not at all, unless provoked somehow. In their practically motionless hordes, some occasionally wormed their way to the top while others sank to the bottom, sometimes biting each other or those bothering them. Larvae from other planes were known to struggle more in an effort to survive, such as ones from the Shadowfell that attempted to escape.

Abilities
Although pitifully weak, the fangs of soul larvae were still dangerous and caused those bitten by them to bleed profusely. They also harbored a deadly, degenerative disease that could result in painful skin rotting for those bitten. Three weeks into the illness, a victim would need to lie completely still to avoid further health risks but death would still come after a month with only cure disease magic as a viable cure.

Combat
Only when compelled to by a more powerful entity would larva of the Gray Wastes swarm their assigned foes. Otherwise, they generally left others alone even when a mortal was in their midst, although it was possible to drown in a sea of the wriggling worms when they were packed closely enough together, an experience that often proved extremely traumatizing.

Society
Soul larvae lacked any kind of society or culture of their own and to most were mere children's horror stories used to scare them straight, but were immeasurably important to those of the Lower planes. Larvae were the epitome of untapped, evil potential, able to serve a myriad of purposes throughout the evil-aligned planes. In terms of economy, soul larvae were a form of basic currency for night hags, evil deities, liches, devils, daemons and demons. They were worth approximately 1,000 gold in the Abyss, although its denizens rarely used material payment. They could be used as food, especially for entities that required life forces to survive such as liches, or as a kind of base "soulstuff" for dark rites requiring esoteric components.

Most importantly, soul larvae were a foundation for several populations in the Lower planes, and given the incalculable amount of fiendish life lost in the Blood War every day, a number that only ever seemed to increase, such creatures were immensely useful for restocking armies. Soul larvae, as the tabula rasa of the Lower Planes, could be used to create new fiends by devils and demons as needed. To some, all larvae were equally pathetic and so selection was randomized while others were more discerning. Once transformed, they were just as likely to reach the pinnacles of their respective societies as any other member, but the number of larvae that rose past the lowest rung was abysmally low, much less the number that managed to become true fiends at all. It was claimed that larvae that showed particular evil potential were allowed to skip the unthinking castes of demon and devil society and immediately become lesser members. Larvae were the primary, if not only way to create quasits and imps, which harvested souls from mortals to further increase fiendish populations, thus allowing they themselves to advance, making them crucial to Lower planar ecology.