The fight begins (likely) with an attack from Évêque. It's a slow windup similar to what you've faced with Lanceliers with one hit. You'll see this attack multiple times throughout the fight, so do ...

Dualliste is the boss in the Forgotten Battlefield area of Clair Obscur: Expedition 33. Here's how to deal with the tough first boss of Act 2! Resistances: Resistant to Fire Weakness: Weak to Light.