Taint is adopted, in part, from Legend of the Five Rings. However, unlike in that setting, Taint in Monvesia is not a result of personal choice or action--it is the result of public belief and perception. Monvesian Taint is further inspired by the Taint from the Thaumcraft mod for Minecraft; as well as the Blight from Dragon Age.Taint is a "psychosomatic" disorder--that is, it is a mental condition that alters the physical body. From a metaphysical, cosmologial perspective, it originates in Limbo (the Plane of Subconscious Thought). Here, the subconscious minds of all living creatures connect; and a collective unconscious "shadow" exists--an iridescent, black and purple storm-cloud dominating the horizon.
When one is transformed by Taint, it effects one at the genetic level. A victim of taint becomes another species. Tainted races are called goblinoids by Monvesian races, or orcs by humans. These races breed true and can expand through traditional procreation. It can be "cured"--a feat which led to the creation of the halfling race (from gnolls which had evolved into boggarts).
It has been suggested by goliath loremasters that the original Taint was created by the HMDJVNW in order to better subjugate their goliath and human servants. By keying it to the collective unconscious, HMDJVNW took advantage of mob mentality: The more your fellows are afraid of you and your actions, the more likely you are to become the monster they fear (orc or ogre). To this day, persons or people who, for any reason, are publicly ostracized from their peers are in the greatest danger of becoming Tainted--unless you are possessed of a particularly strong self-awareness and will.
The Monvesian strain would have been created when the elder strain encountered a new collective unconscious for the first time--one composed of dwarves, gnomes, and rakasta (see below concerning elves). The races of the new world were transformed by the goliath fears of them (goblins, hobgoblins, and gnolls; later boggarts). When Monvesian cultural fears were turned back on the newcomer races, it caused humans and goliaths to transform differently than they had before (creating bugbears and trolls). However, since Desolation-era fears were so ingrained into its refugees, the elder strain survives alongside the younger.
Because of their innate connection to Faerie [Feywild], elves and half-elves are immune to Taint. This connection to Faerie also prevents these from ascension to immortality; instead, it grants them the ability to transcend into faerie beings. No other race has proven to have the same kind of connection to another transitive aspect.
The planetouched races are similarly immune to Taint, due to their connection to the core elemental or energy aspects of the spheres. This includes the Aerites [Air Genasi], who are born of the fundamental Aerosphere instead of its transitive periphery. Unlike elves, however, planetouched are capable of achieving immortality; in fact, the process is actually easier for them, since they already have the attention of one of the Spheres.
Game Mechanics of Taint
Research and treatment of Taint was used as a plot-point in my previous campaign, utilizing knowlegde-based skill checks instead of saving throws. Characters of absent players began to succumb to Taint--one human slowly transforming into a bugbear, and another an orc--but this was used as a device to keep the characters relevant to the story in the absence of their players. The former, after being "cured" by a new character, would later be possessed by her intelligent sword for a time. Oh the dangers of not showing up for regular game days!Like temperaments, skill checks related to Taint are made using the skills Arcana (the lore or nature of Taint) and Religion (its treatment; spiritual guidance as psychotherapy). Should a save versus taint be necessary, these would be Wisdom (early stages) and/or Constitution saves (later stages).
Edited September 13, 2018.