From the back cover of the Baen first edition: "Torn between two worlds - Having won her at great peril, young Aidan, a powerful but not very ambitious magician, would be content to enjoy the fruits of peace with Ailanna, his Faerie love. But Ailanna's dying mother has revealed to him that he is half brother to the king - and requires of him that he provide magical aid to his embattled royal brother. Aidan perforce must yield to this dying maternal wish. Alas, to win Ailanna in the first place. Aidan has also sworn a mighty oath to the Lord of Faerie. Caught between these conflicting vows, torn between the mortal world and the lands of Faerie, Aidan is about to learn the perils, even for a magician, of serving two masters."
Source · ISFDB CC BY 4.0