I grieve to see Ost Elendil in the hands of the Enemy, ${PLAYER}. The great palace of the kings should lie untainted by the forces of evil, not brought low by the machinations of Angmar and its regent!
Fell spirits and their Angmarim masters now stalk the halls of Ost Elendil at Amarthiel's command. We must drive them forth.
Defeat the spirits within the palace and take from their Angmarim masters the blood-stained runes with which they are commanded. That may lessen Angmar's grip on the palace, shining jewel-that-was.
Fell spirits and their Angmarim masters can be found in Ost Elendil, beyond the bridge of Ariant.
You should defeat the fell spirits inside Ost Elendil and collect the blood-stained runes used by the Angmarim there to command them.