Excerpt from ” Theories on Undead”, by an unknown author. Unknown circulation era, due to this work being considered illegal.
There are two methods in which the Undead can arise; naturally and artificially. Examining the natural method of creation, the Undead are the byproducts of a combination of an environment’s latent magical energy with one or more moriums of an unrighteous or tortured soul (known as a “dimsoul”). Essentially, the Undead are a byproduct of one or more moriums that have a portion of a dimsoul “leaking” its will upon an area that is either naturally receptive to the creation of magic or an area in which has been saturated with the heavy use of magic. Additionally, in order for the “creation” of Undead to occur, raw humanoid materials (such as corpses or skeletons) are often necessary, but not always required; the type of Undead that can result from the interaction of a dim soul morium and its environment can vary based upon a number of factors. For example, a mass grave site will most assuredly produce Undead that are created from human remains, while a less corpse riddled area may in fact create perverse spiritual entities derived from the nightmares of the dimsoul in which it was spawned from.
...in order for the “creation” of Undead to occur, raw humanoid materials (such as corpses or skeletons) are often necessary, but not always required; the type of Undead that can result from the interaction of a dim soul morium and its environment can vary based upon a number of factors.
The process in which a dimsoul spawns Undead creatures is completely autonomous and is not in anyway a sentient act by the soul that inhabits the morium. Rather, it is a peculiar and extremely rare byproduct of a small remnant of a tortured or unrighteous soul that invariably extends its willpower over latent magical energies within an area, thusly resulting in the dimsoul extending its misery, hatred or fear into the mortal realm via. the use of magical power. The larger portion of a dimsoul that a morium holds stored within it will invariably lead to the faster and more plentiful creation of Undead, and coupled with an area rife with previous magical use, can result in a single dimsoul morium creating up to a dozen undead. The actual act of a dimsoul morium creating an undead is but a single spark; a brief but violent infusion of the dimsouls’ misery, contempt, hatred or violence into a suitable host made sentient and whole through the latent magical energies coalescing into a creation spell of sorts. Larger dimsouls invariably create more sentient Undead, but a dimsoul will never pass along it’s former soul’s consciousness or memories; only the driving emotions behind what makes it a dimsoul.
Areas that are saturated with Undead through non artificial means are normally the result of numerous dimsoul moriums extending their will into environment (which, for areas such as battlefields, hospitals, mass graves or site of mass casualties, a single human could potentially create dozens of moriums from their passing). It appears there is some sort of resonance effect with multiple moriums in an area in which Undead are actively being created, as other dimsoul moriums are far more likely to infuse the spark of unlife into human remains if the process is already underway nearby.
The process of creating Undead within an area can be manipulated artificially through many different means and methods, the most common being seeding an area with extremely strong dimsoul moriums and casting various high power magnitude spells within an area. It is believed there are also spells that can also help jump-start the “leaking” process of a dimsoul morium, thus creating a chain reaction within a suitable area to saturate it with undead. Furthermore, it appears that through the use of these sorts of artificial seedings, the undead spawned forth are sometimes controllable (to a minor extent) by the necromancer responsible for such a heinous and unnatural act.