Lichdom

Lichdom is a state of undeath in which a powerful Dead Magi has, through an esoteric ritual known as the 'Thirteen Abyssal Steps', locked their soul within their body and then committed suicide. The result is life seemingly unending, the Magi living on as a Lich, a skeletal sorcerer retaining the full knowledge and memories of their living self. Due to the nature of the ritual, nearly all Liches in history have been necromancers, and have continued to focus in on that art into their undeath.

Nine of the Thirteen Abyssal Steps are known, and Four forgotten (known as the Four Forbidden Steps). It is unknown if knowledge of them is truly lost or if most Magi purposefully destroy any knowledge of them in an attempt to deter attempts towards the art, as Lichdom is considered highly foul in most societies. The steps in order are found here.