Wormspawn

Appearance:

Wormspawn are bred doppelgangers, and they can appear as any living organism of medium to large size. Superficially they mimic the appearance of whatever race or even specific individual they were created to copy, but they are not an especially good copy. The flesh is bloated in places, sagging off the skeleton in other places, and the gait is fluid and unnatural. They also have a fairly specific and offensive odor, not unlike rotting trash, human waste, and cloves.

They cannot speak, and they are technically naked, as their exterior is a crafted husk. Thus, certain things will look off under closer inspection, what looks like metal armor has more of an organic fish scale luster than metal, and it will be somewhat pliable. If the person being mimicked was wearing armor with a closed visor, this is what the wormspawn looks like, and opening the visor of their helm is actually the wormspawn opening its mouth.

Behavior:

Wormspawn will actively work to consume as much biomass as possible and will attempt to capture living beings and creatures to drag them back to their lair. Otherwise, they are very dull-witted, and aside from the ability to hide and go unnoticed, they have no real skills. If threatened, a wormspawn can release a loud shrieking noise, and produce a highly offensive odor. One draws other wormspawn to help the threatened creature, the other causes nausea in creatures around it. It can be hard to press an attack while fighting the urge to vomit.

Purpose:

Wormspawn are the offspring of a Mother Worm. A Mother Worm is a massive creature, often dug into the basement of a building or a dungeon. It will consume whatever its spawn brings it. It then will create more wormspawn to serve it. Unlike it's spawn, a mother worm can be very intelligent, and can and will make deals with sentient beings. Those who are not useful, or malleable to deals are eaten and turned into worm eggs, more wormspawn, or shit. Those who agree might get off with having the mother worm plant one of her mind worms into their head, through the sinus cavity. This worm in the brain cannot control the host, but it can link back to the mother worm, share emotional information, and be induced to help or harm its host.

Worm-Ridden

A Worm-Ridden is a normal sentient being with a worm in its brain. Its emotional state is routinely being sent to the mother worm, so mother knows when they are scared, injured, plotting deceit, and the rest. These individuals are the leaders of the wormspawn and organize the slow occupation and consumption of a given area. To this end, when a worm-ridden does something to please the mother, the worm will cause their brains to release pleasure hormones. To serve the mother is to know pleasure above any other. It can also cause anxiety and tremendous amounts of pain to the host. If threatened, the worm can stimulate the adrenal glands, so that a normally complacent barkeep can suddenly have tremendous strength and the ability to ignore pain, up until their body collapses from massive internal injury.

Fighting Worm-Ridden and Wormspawn

Spells that dispel evil, or cleanse the body can destroy the brain worm parasite. Wormspawn can be turned like weak undead, and are highly vulnerable to acid and fire damage.

Usage:

Wormspawn are a nightmare scenario. PCs shouldn't find one, they should find several, dozens, maybe even an entire village overrun by them. They aren't limited to humanoid shapes, the livestock can be wormspawn. They don't do a lot of damage one on one, but they are filthy creatures. Wounds they cause fester and become infected, and have a high chance of being laced with worm eggs. An untended wound can see a person turned into a half-Wormspawn. Their body is slowly being filled with worms, hatching, and breeding inside their body. The bite/wound site will have a massively bloated appearance, writhing with the mass of worms inside it.

After a Wormspawn is 'slain' they will burst and become a less dangerous but more disgusting swarm of worms. These worms have little chance of harming a foe, other than delivering minor wounds that can, as above, fester and turn the victim into a new host. Incapacitated foes can be consumed by worm swarms. A person badly infected with worms will often be the first victim if they are attacked and the worm bloat is ruptured. Slashing open a bloated leg to purge the worms inside can cause them to go into a frenzy, digging deeper into the host for warmth, safety, and food.

Once a host is overcome by work infestation, they become wormspawn and will return to the mother worm so that it can consume them, and release new wormspawn in their image.