The End of All Things — Robert Kroese

One by one, the powers that threaten the land of Orszag have fallen. Only the demon Arnyek remains. Immortal, uncaring and unstoppable, Arnyek waits far below the ruined city of Nagyvaros for the day he is free to destroy the world. Desperate to stop him, Konrad the Sorcerer plunges into forbidden magic and turns against those closest to him. But Konrad must learn a difficult lesson: no matter what path he takes, he cannot stop the End of All Things.