The Silver Mage (The Silver Wyrm #4; Deverry #15)

Read Katharine Kerr's posts on the Penguin Blog.

The Horsekin are assembling along Prince Dar's northern border, and the Deverry alliance doesn't have the men or resources to prevent their enemies from moving into the wilderness areas known as the Ghostlands. But then the Dwrgi folk and the dragons come to Dar's aid, tipping the balance in their favor and offering Dar's people a chance to defeat the Horsekin once and for all.