Seven Altars of Dusarra, by Lawrence Watt-Evans, The Lords of Dus, vol. 2

In the second book of the Lords of Dus series, Garth of Ordunin had been set a new task by the Forgotten King: Bring back to Skelleth whatever he found upon the altars of the seven temples of Dusarra. As he went about his blasphemous errand he learned more about the Dark Gods -- and more about his own destiny!