“Shadow Scale” by Rachel Hartman

Shadow Scale, the sequel to Seraphina, a 2014 Top 10 title, picks up where Seraphina left off, with the Queendom of Goredd coming to terms with the existence of half-dragons, a civil war among the dragons themselves after an act of betrayal, and the risk of that war spilling across their borders.

When war eventually breaks out between the dragons and humans, Seraphina must travel the lands to find those like herself—for together they will be able to fight the dragons in powerful, magical ways.
 
As Seraphina gathers her crew, she is pursued by humans who want to stop her. But the most terrifying is another half dragon, who can creep into people’s minds and take them over. Will Seraphina play it safe or risk everything?