Defeat White Lion Magicians around the Lost Mines. Afterwards, speak to Candace Shagwell at the Entrance to Lost Mines. Use your quest tracker to see your progress.
Candace Shagwell: Some of those White Lions are really, really naughty. Did Candace Shagwell: you hear that many of them use forbidden spells? NakanoAzusa: Forbidden spells? Candace Shagwell: It converts the vitality of a pure-souled human being Candace Shagwell: into luscious mana. The target that the spell was cast Candace Shagwell: upon simply dies. Wanna know what's even more Candace Shagwell: naughty? NakanoAzusa: What is it? Candace Shagwell: La Cidro is very active in Karena. There's a painfully Candace Shagwell: large number of missing children over there. HiiragiKagami: You don't mean... Candace Shagwell: They're sacrificing the poor kids. Let's defeat them before Candace Shagwell: they take more innocent lives.
Reminder Dialog
Candace Shagwell: These nutters aren't as easy as I'd like them to be. I Candace Shagwell: know that you can finish the job, though.