They exist in phylacteries, and if slain, the phylactery will simply form a new body for them. In order to slay a lich, the phylactery itself must be destroyed. Lichs are usually powerful ...

This quest first starts out by looting a Lich's Phylactery. This strange dark jewel radiates dark power. If you touch it, something whispers in your mind. Well of course you are going to touch it!