The Dawn and Its Light by Piper CJ
All that remains...
If Nox and Amaris are ever to have the life together they've always hoped for, they will have to use all the power and strength within them to protect their continent. When powerful enemies from Sulgrave wielding unspeakable access to magic threaten to shatter their world for good, they must join with Raascot's military, the reevers, and an unlikely ally from the mountains to have any hope of saving their kingdoms. Together, their forces press north across deadly wastelands, facing unknowable threats, impossible battles...and new questions of what their fate truly holds.
Their entire lives have been building toward this moment. Caught between faith and frenzy, questions and identity, love and lust, past and present, Nox and Amaris's story draws to an explosive conclusion as they fight once and for all to protect their people, their future, and each other.