Harry Turtledove 
Sceptre’s Return 

For hundreds of years, the rulers of Avornis sought to reclaim the Scepter of Mercy, their only protection from the fallen god known as the Banished One. They all failed. Now the burden rests on the shoulders of two kings divided by pride, but united in duty…King Lanius has crafted a daring plan to recover the Scepter – a plan that must remain utterly secret lest the Banished One discover and thwart it. But the Scepter lies far to the south, in lands held by the Menteshe tribes. Lanius will need help from a military man – King Grus.King Grus answers the call. Civil war has broken out among the Menteshe, distracting them from guarding the Scepter. While King Grus fights his way to the citadel that holds the sacred talisman, Lanius puts his plan into action.But the worst nightmares of Lanius and Grus are about to come true, for the Banished One is aware of their every move…