The Dread Prince (Dread Descendant #2) by Lauren Cate Leake

Magic is different in the Dread Lands. Magic is deceptive in the Dread Lands.

At last, The Dread Prince takes the throne and begins to develop his own army while battling the darkness that still lurks in the ancient and deadly Dread Lands. Maeve is grieving a great loss as Mal slips into darker and darker Magic, driving a wedge between them. War looms with the other realms, and Maeve and Mal question the dragon-shifting High Lord of Aterna's loyalty to their cause.

The sequel to The Dread Descendant brings you further into Maeve and Mal's world of darkness.