The Gods Return — David Drake

The Isles have been more or less unified under Garric's rule, but the Change that created the continent has removed the old Gods of the Isles from reality and released other Gods from other planes of existence.

Now the servants of the forbidden Gods of Palomir call forth The Worm, an ancient thing that threatens to devour all life in the newly formed kingdom and make way for the reign of dark Gods, newly awakened to ambitions of worship and dominion. Some are bad . . . and some are worse.