This tutorial will explain how you can unlock the Flames of War trophy in Jeanne d’Arc.
The game will introduce the Burning Aura feature on the third stage. Jean will also be joining your party for the first time, allowing you to double stack the Burning Aura.
For this trophy to pop on, have Jean attack with his spear two spaces away from the enemy to create a Burning Aura. You should then move one of your other characters in front of Jean and then attack the same enemy to create a double stack.
Afterwards, you should have another character stand on the Burning Aura, and then attack the same enemy to unlock this trophy.