Onyx Storm book by Rebecca Yarros

Onyx Storm by Rebecca Yarros is the third book in the Empyrean series, following Fourth Wing and Iron Flame. As war spreads across the continent, Violet Sorrengail must leave the safety of Basgiath War College to seek powerful allies, uncover long-buried secrets, and fight to protect those she loves. Filled with dragons, dangerous magic, romance, and high-stakes battles, the story raises the stakes with shocking twists and emotional moments.