Dark Horse by Mary H. Herbert
Paperback. Condition: Good. 1990. TSR Books. 1st Edition, 1st Printing, Stock Image.
Book #1 in the Gabria series.
After her entire clan was massacred, a young woman assumes her brother's identity and becomes a warrior - all to exact revenge upon the chieftain who ordered her family slain. But the chieftain, Lord Medb, has resurrected the forbidden art of sorcery and plans to destroy all who oppose him in this dark ages fantasy world.