Speak with Jack of Truths with Margrid the Sly in your party to enter this mission. If your character chose to follow Master of Whispers (after the primary quest Mysterious Message) and has not yet gained Margrid, you can still enter this mission by partying with another player who can bring her. You don't need to finish Master of Whispers' side of the storyline by completing the Rilohn Refuge mission. Rescue Kormir from Gandara.