Beldan's Fire

From the back cover of the Tor first edition: Once upon a time the land of Oran was a land ripe with magic - magic drawn from the powers of nature. Air. Water. Earth. Fire. Four women representing each of these guarded the land, until the Fire Queen destroyed the other three and began her oppressive 200-year rule. She has banned all magic in Oran but her own, killed all children who possess it... yet some of these have escaped her notice, banding together on the city streets or escaping to join the men and women of the rebel army that calls itself the New Moon. Among these magical, desperate outlaws are three unlikely women who carry the power of earth, air, and fire. Now all they need is water magic... and the final battle can begin.