The Beasts We Bury - D. L. Taylor

In a world where dark magic hovers on the horizon, two teens must decide how far they will go to break the system that has them trapped. Mancella, heir to the throne, emerged from the mysterious Broken Citadel with a strange and violent magic: she can summon an army of animals, but only by killing them first. Silver is a charming thief who plans to manipulate Mancella in order to pull off a once-in-a-lifetime heist. When her father decides that Mance should kill a human in order to create an unbeatable spirit army, Mance realizes how much of a pawn she is in his world. As the deception and bloodshed continue to mount, Mance and Silver find themselves forced to make choices that will change the realm forever.