The Wizard of Karres

Blurb

The Wizard of Karres is a novel by Mercedes Lackey, Eric Flint, and Dave Freer that was published by Baen Books in 2004, as a sequel to The Witches of Karres by James H. Schmitz.
The book uses the same characters as the original novel, and starts about where the original ended. The story describes how Captain Pausert is found to have klatha powers that increase over the course of the story, where he is called a witch, a "hot witch", and finally a wizard.