Below is a walkthrough for A Mage’s Miscalculation subquest in Valkyrie Elysium.
Obtained: Speak with the Spirit in a small room during Chapter 6 just before the seventh Storage Camp (Eastern Temple).
Objective: Find the Magic Tome
Follow the path until you reach the end where you’ll find a gate. Head through it then enter the house and go upstairs. Next, open the chest on the bridge then jump down and fight the enemies. Once you defeat them, open the chest to complete the quest.
Rewards:
- Fire Lance III