There are books in the Agranor library that explain some of the game's features and help you understand how to create strategies to defeat certain monsters in the game.
I recommend reading them. In this case, for example, you need to focus on fire elements spells and adjust Celica to your opponent's weaknesses. For example, add willpower, magic power (arcane), and speed to her. I'm not a strategy genius either, but these parameters help me with many fast opponents.