Amestris is a guardian spirit of an unknown element, likely no element, and one of the many soldiers in Anlortim's Golem Batallion. She is also the lover of Xerxes, one of the army generals. She is Xerxes right hand and shares Anlortim's Stone Sleep ability, turning to stone in daylight.
Trivia
Amestris' name comes from Amestris, the wife of Xerxes I of Persia, whom her lover is also named for.