"I swears there is something foul in that cave, humid and hot like a swamp. A foul stench like the breath of some horrid beasty. Ain't nothin' natural in there."
A Nidus is a mix of plant and animal in a horrifying manner, these things are one of the few remaining marks from the Far Fracture early in the world's history. These lifeforms were able to take root in the most dangerous and inhospitable regions of the world, often deep underground. There is a central part of the Nidus but their body extends out far forming its own ecosystem in some places, and from this ecosystem, strange creatures can form even aberrations.
Using a Nidus in gameA Nidus by design is not so much a single monster to be defeated, they are living dungeons that have existed since before time when the world was still new. While the other aberrations were hunted down and slain the Nidus serves as the last remains of the aberrations thrust into this world. All other Aberrations on Savorah come from these, as such, they are extremely difficult to entirely root out. A Nidus will have a daunting health pool at first but this is because it is made of multiple parts. Each 'room' of the dungeon that the Nidus both is and inhabits grants the creature more health, attack options, better saves, and so on. Players must find in these rooms what are known as 'Nerve Clusters' these are unfortunate creatures that have been absorbed into the Nidus fusing into the biomass usually in a wall but it can vary. They have some form of protection usually something like a rib cage or hidden inside the flesh walls. The larger the space the more advanced a nerve cluster, a particularly large area might have a beholder fused into the walls, while mostly dormant they can awaken and attack. A Nidus can't be snuck up on so long as the creatures inside of it are walking on it, hovering or flying creatures can carefully move around avoiding membranes, hairs, or sensory organs within. Clever players can still maintain sneak attacks by finding ways to not stand on the Nidus itself. At the center of the Nidus will be the core, which functions as brain and heart is how a Nidus can be killed and will be weaker for every Nerve cluster destroyed. Should players sever connections around a room that still has a cluster and defeat the core that cluster will become a new core within a day. From there it will begin reaching out again trying to reconnect to the slain clusters to regrow itself. A Nerve cluster can't avoid attacks easily, and are incapable of taking reflex saves against spells, but they do have resistance to magic (taking half damage from all magical sources)
The core of a Nidus is always within a pool made of pulsing alien flesh containing a thick toxic liquid with the core organ of the Nidus, a brain in the shape of an eye with dozens of roots coming out of it sticking into the pool. From this core the alien flesh begins to spread out in the surrounding area, no one is sure how this process works as it seems to defy all the known needs of life. They require no food, no water, no magic, or seemingly anything to grow larger, that said there seems to be a fascination of the Nidus to collect the brains of its victims in the toxic pool. If one can do this for long enough they can grow quite large and can create other aberrations. The worst-case scenario is creating a Centoculus a massive mix of beholder, purple worm, and centipede as these creatures are extremely difficult to destroy.
Alien flesh that grows along walls, floors, ceilings, on any surface and even through surfaces. It isn't uncommon for a Nidus to create large caverns their body breaking the ground away and even incorperating it in sections. A large enough Nidus can even be a dungeon itself with traps and doors made from itself and the ground it removed.
Genetics and Reproduction
It is hoped that the only such creatures in existence are from the Far Fracture but there are those that think that should a section of the Nidus be cut off from the brain it could form a new Nidus and begin to expand again. A newer idea suggests that something akin to an Intellect devourer is used as a means to spawn a new Nidus by taking over a humanoid body and moving somewhere else and turning that body into the start of a new Nidus. It is also assumed that any spawn of a Nidus shares the knowledge and can possibly even commune telepathically over vast distances.
Growth Rate & Stages
Thankfully the growth rate of a Nidus is slow, often taken decades to turn into a sizeable threat but they are also very difficult to eradicate as there can sometimes be secondary pools for the Nidus to regrow its brain and resume growing. In most cases where a Nidus is known about every effort is made to destroy it, but mostly results in a delaying measure.
Ecology and Habitats
They prefer areas that are as inhospitable as possible, this protects them as they slowly grow. Should one manage to take hold in an area with a more favorable habitat they can grow quickly but are often found out faster. An example could be within the sewers of a city where they can feast on creatures that come near.
Dietary Needs and Habits
While they do not require psychic energy to feed, being in an area with more intelligent life does allow them to grow faster as if feeding off some energy coming from the gathering of minds.
No Nidus has thus far been domesticated, though they have in the past domesticated other creatures. The Silkspinners in Nefra are thought to originate from a now-dead Nidus, at least the belief is that the Nidus is dead some scholars believe the Nidus likely changed its form into the Silkspinner queen after creating them and feeling threatened enough to abandon its body.
Uses, Products & Exploitation
One possible use, if you can manage to open a dialogue with the creature through one of its various creations is gathering knowledge that the Nidus knows.
Geographic Origin and Distribution
There are known Nidus' beneath the Scar Desert, the Carvethian forest and the ruins of Khel Khulthur, though many fear the vast empty caverns beneath the surface world likely has large amounts of undiscovered Nidus.
They have all the knowledge of the ones that created them, as well as knowledge gained through their lives. The older and more powerful a Nidus becomes the more they know about the world and the more their own personality is shaped.
Perception and Sensory Capabilities
The Nidus can sense thoughts that enter into its area of influence, which is 100ft beyond its body. The Nidus lacks eyes or ears but it is aware of itself and the shape of its body.
Civilization and Culture
There are no genders to a Nidus, If they refer to anything it is by their species.
Interspecies Relations and Assumptions
Other species are food or thralls.
Destroy on sight
No observed maximum
No observed maximum
No observed maximum