There are multiple types of quests you will complete in Disciples: Liberation. One of these quest types is Companion Quests. These quests deal with a specific member of your party. The first one you may discover is Corisandre’s Calling. This quest can be found by traveling to Port Grimard in the Plains of Widows.
Before you can begin this quest, you will need to recruit Corisandre from Equisheim. Once you have her in your party, head east across the bridge and speak to the Captain of the Merchant Fleet. He will give you a quest to locate the source of the plague.
After collecting the quest, head back across the bridge you came from and head slightly north to find the Church of the Highfather. This is a dungeon that you can enter.
Go inside and take the path on your right. There will be some battles along the way. This route will lead you to a room with a torture table and a few dead bodies. To your right will be the Mirror’s Eye. Interact with it to have Corisandre destroy it.
With the Mirror’s Eye taken care of, head back to the Captain of the Merchant Fleet to find him dead. Corisandre will run through the streets and realize that she can’t heal anybody. After talking to Corisandre, you will unlock her world skill that allows her to cleanse corruption in the world.