Powered By Ghosts by Kaje Harper

An untrained sorcerer and a reclusive necromancer face a ghost-infested town.

Darien is free of his dead invaders, and his eyes have opened to a new reality. In a world of sorcerers and necromancers, he’s full of power and potential, but completely ignorant. Necromancer Silas, and Silas’s cat familiar, Grim, are teaching him basic skills, but danger won’t hold off, just because he’s not ready.

Silas never planned to share his life with anyone, but after a week of shared battles and shared nights, Darien has become a fixture in his home. Silas has never met anyone with more raw magical ability, or less idea what to do with it. When Silas is offered a job hunting ghosts, he’s tempted to refill his depleted bank account, but reluctant to bring untrained Darien along. Darien’s eager to help, though, and eventually Silas gives in. It’s just a few ghosts. Nothing he hasn’t handled before. What could go wrong?