A Wizard in a Feud — Christopher Stasheff

Under the nom de guerre of Gar Pike, renegade psychic wizard Magnus D'Armand travels the stars fighting injustice and oppression, like his father, Rod Gallowglass, the Warlock in Spite of Himself. But unlike his famous father, Magnus refuses to play by the rules, sowing the seeds of freedom and revolution throughout the galaxy.

A Wizard in a Feud

When Gar and Alea land their ship on a planet for computer system maintenance, they aren't expecting to run into Fairies, Wee Folk, Druid priests, and feuding clans transplanted from Scotland and then forgotten. Can they, along with two courageous exiles and the psychic power of the Fairies and Wee Folk, bring peace and order to this world?