'The text you recovered told of an evil woman of the Hillmen who betrayed her tribe to serve the False King. Now she dwells within Minas Agar, commanding the Angmarim who pledge allegience to the Iron Crown.
'Is this a legend of old or are these the words of truth? That I cannot say, but Mordirith's servants are many and powerful...I do not doubt these claims.
'You should investigate the matter. Return to Minas Agar and strike its gates. Should this fabled champion exist, she would be ill-advised to ignore such a challenge.'
Background
Lindir translated the text you found from the Black Speech into Westron.