A Line of Blue Fire by D. M. Recktenwalt

There is a power in the land. The mages have long known of it, and drawn on it. But the world is in flux, the gentle ways of the Mother being threatened by the growing influence of Her Brother/Son H’lal, the Warrior God.

Hagen Templeborn is a product of both, born to a Priestess of the Mother, and sired by an angry, ambitious Priest of the new god. Along with his foster brother and sisters, he is student to the traveling mage Tanqui de Laqline, devoted to She Who Made All, who now walks the treacherous path between old and new.

Once on his own, Hagen becomes mage to the village of Kendorn, offering advice to the village council and serving as teacher to a number of students. When Mason Alderson comes to him, Hagen recognizes the lad’s talent -- this is the one student for whom he has hoped. But he has no idea that the Mason’s arrival will change his life forever, that together they will meet the mythical creatures known as arabesques, and that he and Mason will ultimately face one of the greatest challenges of their lives.