How to Complete One Last Memory
This quest appears after you have completed Devil's Pact.
The objective of this quest is to defeat Duke Snakeheart, who is a Nu Mou Arcanist. The other foes, which you can ignore if you prefer, are a Parivir, Seer, Scholar, Flintlock, and Defender. Maquis is a guest unit in this battle, and he can't die, so don't bother healing him.