Okay, so the description can be condensed to make it easier for the reader to grasp:
"A story of second chances, lost destiny, and the fire of past lives.
Betrayed on the battlefield, the legendary commander Kael Ardyn is reborn in a new body. In a world of magic, his soul takes on the form of a peaceful flame. To understand the gift and curse of his rebirth, he journeys to the Royal Academy of the Flame.
There, he meets Lyra, a girl who wields icy fire—its opposite and complement. The two discover they are part of an ancient prophecy about a duo known as Phoenix and Frostfire.
While searching for the lost journal of former mages, they uncover a conspiracy that reaches into the heart of the Academy. To survive, they must unite their powers and hearts before the history of their past lives repeats itself once again."
Leave some secrets in it, don't hand everything on a plate.
Chapter 0 isn't necessary; we can leave it as elements of the protagonist's memories, especially since the next chapter begins with an image of the war.
Everything generally happens too quickly, and we don't have time to get to know the protagonist or familiarize him with what's happening. Start the story a year before the Academy (1 or 2 chapters); this will make it easier for readers to immerse themselves in the atmosphere and world. Also, add more dialogue between characters to make the world feel more alive.
I wish you luck, because I see a lot of hard work and the foundation for something epic in this.
