Ignited by Magic by Katy Haye

Powerful midsummer magic will be unleashed. For good or ill.
Kyann and the four kings have raised an army against the Stalwart Emperor. The battle between the two sides will settle the future of Charnrosa.
As they encounter new threats and old enemies, Kyann must accept her destiny as guardian and embrace her long-rejected magic if she is to save the Empire she loves.
One girl, four kings, and the magical destiny that binds them.