Liches are a type of Undead Necromancer both famous and infamous for being the most successful at maintaining their intelligence throughout their long undead existence - at the cost of the lifespan and souls of other people. The rituals to become a lich remain an exclusive secret. Though the methods are thought to vary, their commonality is that all liches end up wearing the skull of a dead animal or creature, which ends up fused to their bodies, partially by the help of the plant-life called Lichen that grows across them (and sometimes forms into entire cloaks). Liches are also thought to be able to place lichen as a magical ward for spying. Their eyes take on strange new colours in their sclera (often dark) and pupils, and additionally, the bodies of liches are also known to have grown around half to twice as big as they once were - perhaps merely a Transmutation done in order to appear more authoritative (Liches are popularly thought of as vain to an extent).
Necromancers who fail their attempt to become a Lich can see their bodies rot away and minds stuck in the skulls they attempted to bond with - becoming a type of Flaming Skull.
For a period, Liches were accepted as a presence in the countryside of at least parts of Mogxa and Ferweth, potentially inspired by the Icen Maiden’s approval herself. During this, a Lichen Villa system was practiced in which liches built elaborate Manors where they could gather libraries, research Magic, Alchemy and other natural philosophy and sciences, served by a number of Servants. These Servants got to live rather stable and relatively affluent lives, in exchange for them giving up parts of their lifespan to the Lich - in theory saving the lich from having to collect entire souls and thereby kill people to maintain their lichdom. It’s disputed whether this really was enough, or if the Liches continued taking sacrifices, and also to what degree the contract for the servants was fair. Those who defend it are usually those most in favour of strong feudal and Social Hierarchy, or those who deem the pursuit of knowledge as highly important. A number of inventions were discovered by Liches.
It is unknown whether Liches need diamonds as an ingredient like a number of Resurrection spells do, and therefore to what extent the Diamond Crisis was caused by or affected Liches.
Today, the taboo against necromancy and undeath has reached Liches again, especially amongst the common folk. To many rebellious peasants or republican merchants and city-dwellers, liches represent their vision of a sophisticated front hiding a gruesome and tyrannical villain.
Their use of skulls for their bodies, as well as the common use of bones, teeth, claws and such for their attire has lead to the Kholo who do similarly being compared to Liches, causing negative stigma.