Kiska

Jarl Hawkins is a modern spaceman marooned on the planet Vanir-a backward world with sorcerers, black-powder weapons, nomad raiders, and church seeking to become all powerful.
He has lost track of his friend, the great wizard Kvasir Haroldson, and is desperate to find another wizard who can help him get off Vanir and back to his home world. He instead discovers a witch, Kiska, who is one of the feared northern nomads, and who has been banished to the mountains for practicing her magical craft. Jarl befriends her, and together they search the Province of Cimarron, the Sabre Mountains, the secret Ghost Raider city of Jorvik, and the magical city of Vor for some word of Kvasir.
But, while they journey throughout Vanir, the King dies and Jarl's friend Will James is made the new king. Vanir is attacked from two directions, and Jarl and Kiska must return to the frontier Province of Kettlewand to help Will James save his nation.