Apenas saindo de palavras-chave, poderia ser A Sombra do Ararat por Thomas Harlan?
The Roman Empire has reached our 7th century without falling or becoming Christian. Galen Atreus, Emperor of the West, and Heraclius, Emperor of the East, join forces to overthrow Chroseos II, Emperor of Persia. The book follows four major characters. Dwyrin MacDonald, a young Irishman learning sorcery, is prematurely initiated and sent to fight with the Roman army, though he can barely control his gift for calling fire. The Roman Thyatis Julia Clodia, a covert warfare specialist, leads her unit behind enemy lines. Ahmet, an Egyptian priest/sorcerer at Dwyrin's school, sets out to rescue Dwyrin but meets Mohammed (yes, that Mohammed). They join Roman allies Nabatea and Palmyra, desert cities facing superior Persian forces without Roman aid. Finally, Maxian Atreus, Galen's youngest brother, a healer-magician, discovers a "curse" protecting the State from inimical magic but also preventing nonmagical progress. He sets out to lift it at any cost, resurrecting canny Julius Caesar and searching for Alexander the Great--an even greater source of magical power.