Lichdom

A lich is the remains of a great mage who embraced undeath as a means of preserving themselves. They tend to further their own power at any cost, having no interest in the affairs of the living except where those affairs interfere with their own. Scheming and insane, they hunger for long-forgotten knowledge and the most terrible secrets. Because the shadow of death doesn't hang over them, they can conceive plans that take years, decades, or centuries to come to fruition.
A lich is a gaunt and skeletal humanoid with withered flesh stretched tight across its bones. Its eyes succumbed to decay long ago, but points of light burn in its empty sockets. It is often garbed in the moldering remains of fine clothing and jewelry worn and dulled by the passage of time.
A lich is created by an arcane ritual that traps the mage's soul within a phylactery . Doing so binds the soul to the mortal world, preventing it from traveling to the Outer Planes after death. A phylactery is traditionally an amulet in the shape of a small box, but it can take the form of any item possessing an interior space into which arcane sigils of naming, binding, immortality, and dark magic are scribed in silver.