Undead

Potential general spoilers

An artifical race made by Rotten King during his Cursed War conquest, despite ultimately losing the war and dying, undead are still numerous race continue thrive on its own. Though due this grim history relations with undead normally are tense, except continent of Quri which was untouched by the Cursed War. Culture of undead nations vary greatly is cannot be properly summarized together, but politically they are best divided on those who denounce Rotten King actions, those who cherish their heritage and neutral.

Undead nations post Cursed War brought concept of corpse trade, where they are willing to buy corpses or kin and sauria in order to reproduce, which often lead to mixed responce depending on culture.

While technically the same, undead are usually divide into civilised and feral depending on their intelligence. Feral ones have rudimentary intelligence, able to manipulate simple tools properly and generally hostile to kin and sauria, but can be somewhat tamed.

Undead hermit
Undead themselves are fairly small slime-like creatures, not able to survive on their own for long period of time and require incubating. Those hermits are supposed to be planted into a carcass, which they will gradually rebuild and reanimate to use as a shell. Depending on a size and state of decomposing, incubating period takes from few days to months, with highly decomposed bodies having risk of death thus more fresh and preserved bodies are prefered.

Hermits are reproducing asexually, carried out by adult undead and being "born" through conveninet orificie, usually mouth which to most kins looks like vomiting. Hermit likely inherit most of parents traits but suffer high mutation rate, so some undead cultures perform "culling" to remove undesired mutations and potential feral undead.

Once planted into a carcass hermits sprouts its roots into tissue and bones, merging with it and never can be able to separate from it. Those roots performs metabolism functions, regenerate tissue, neural functions and possibly grow new tissue which wasn't present in original body.

Hermit memories, personality and intelegence are not tied to original body in any way, and should be considered a completely new person. It is even possible for hermit to use animal body while retaining their self-awareness and intelligence, though is usually frowned upon in many cultures and more feral mutations are used for reanimating animals, with some exceptions.

Limit to what hermit can reanimate is usually size of a body, it should be big enough to fit the hermit and have spare tissue for roots. Plants and fungi are considered immune to undead.

Adult Undead
Once past incubation undead is considered adult, even though they can keep developing further. Undead do not suffer from aging as long as their body is well maintained.

Just like other lifeforms undead also require food and water to function, though their diet can vary creatly depending on original body and mutation. Rest and sleep also benefit them, but have much higher tolerance if there is lack of it. Main difference from the kin and sauria is that undead have significantly slower metabolism and their regenerative abilities aren't universal, what leads to visual degradation of skin and other tissue while maintaining functionality. In addition their body temperature is lower, but tolerance to lower temperatures is significantly higher.

Due all body now rebuilt undead do not rely on majority of vital organs original host had and can ignore wounds which would be too painfull to ignore for kin. Most of illnesses also do not affect undead, except some fungi infections and undead only sickness.

Social structure
Undead have plenty of varied cultures, here are some prominent ones.

Enclaves
Mostly autonomous settlements of undead which cherish Rotten King as a god-father, they generally differ from each other culturally but often unite in time of need. Enclaves normally are fairly small settlements due their hostility, so neighbour try to eradicate their numbers, but occasionally some grow in big cities with biggest known one is Ugaask. Notable that enclaves often have little restriction on use of their nature, so many of them try to weaponize more exotic mutations, utilize ferals in warfare or even construct complex stitched corpses to create terrifying beasts.

North Tarun Grave Kingdoms
Not united under single ruler, but most of them attempt to fix relations with kin and sauria. Very active promoters of corpse trade seeing it much beneficial method of violent corpse obtainment. Feral kin and sauria undead are outlawed and must be culled, though more docile feral mutations are occasionally utilised to reanimate animals.

Origins
All undead originated from Rotten King, who created them as his loyal soldiers. Because big army would require a lot of biomass, which single demon wouldn't be able to create fast enough, it was decided to utilize already existing ones by infesting corpses of dead creatures. So technically all undead are demonkin, but most of them are very deep generation of it.

Rotten Kings plan of exponentially growing army worked well but it hit logistical issues very quickly once army started to grow big. Undead army required supply lines for equipment, rations and commanders to efficiently lead them in battle for more sophisticated strategies. Solution was create more intelegent undead, who would do those sophisticated tasks while remaining loyal. Subproduct in increased undead sophistication was that undead offspring had high chance of random mutation, which could grant them more intelegence, or reduce them back to feral, or give completely new characteristics. Rotten King concluded that mutations are beneficial trait to potentially achieve helpful changes he didn't think of, and due sheer amount of soldier less beneficial ones will matter much less.

After disastrous defeat and death of Rotten King, split off other armies were still aimless ravaging lands, slowly dwindling in numbers without proper supplies. After a while remaining undead realized what happened and either settled or went into murderous rampage until eradicated. At the dawn of undead nations, majority of them were feral and minor portion civilized, with controlled reproduction now majority of them are civilized. Though some cultures never restricted feral population and are still very agressive.