A phylactery is a vessel that contains the life essence of a lich
. The creation of a phylactery is a requirement to attain lichdom; it is a demanding process of black magic
that relies on complex rituals and exotic magical components. The actual phylactery is usually a sealed vessel that contains a focus for the lich's life essence, such as strips of paper with magical phrases inscribed on them, a precious jewel, or even a small piece of the lich's body. After creating the phylactery, a lich lives on forever in undeath
. The phylactery usually becomes their most closely guarded posession, as the only way to permanently destroy a lich is to destroy its phylactery and release its stored life essence.