Pathfinder: Wrath of the Righteous allows you to play as a powerful Lich. You must unlock the Lich Mythic Path to do this. You can learn how to unlock this Mythic Path below.
To unlock the Lich Mythic Path, you must acquire the Wand of Zacharius and return it to Zacharius. The wand is found in the Leper's Smile location, which you will have to explore as part of the story. You do not have to get the wand on your first visit to this location.
Behind where you encounter the Yescavor Queen in the Leper's Smile, you will spot a crevice. Enter it to reach the underground of the Leper's Smile. Once underground, take the left path. You will encounter several Wights, as well as traps that you will have to defeat. At the end of this path is a glowing chest surrounded by stronger Wights. They will continue to respawn until you interact with the chest. After doing so, a cutscene will trigger and you will be offered a choice. Select the evil option and you will receive the Wand of Zacharius.
Zacharius can be found in the basement of the Lost Chapel, a location you must come to during the story. The basement can be found at the end of the Lost Chapel. There are many enemies in the basement that you need to defeat. You will find Zacharius in one of the side rooms. Return the wand to him and he will promise to meet you in the future as well as unlock the Lich Mythic Path.
For more information on Pathfinder: Wrath of the Righteous, check out How to identify items in Pathfinder: Wrath of the Righteous and How to disarm traps in Pathfinder: Wrath of the Righteous on Pro Game Guides.