The Dagger Queen - The Sovereign Blades, #2

Skye Eskel has taken back her kingdom. Despite opposition from all sides and a prophecy promising her country's destruction, she's fought her way to the throne. Yet threats mount even as she secures her position, from the blood cult led by her own estranged sister, to the vicious ghosts they've unleashed. She has new visitors to contend with, too: a delegation from the Imaldran Empire. Skye must navigate the demands of a prince both charming and dangerous, and the offer he makes.
It's one that might finally give her the strength to dismantle her enemies - or end with her crown in the hands of a foreign ruler. And despite all her efforts, the revenants are getting stronger. If Skye can't find a way to defeat both ghosts and Nocturnes, it won't be long before there's nothing left to rule.