'Well met, Name. I am Belvaer, commander of this outpost, and it is an honour to meet you at last. Your deeds are known to us, and it is for this reason that I have devised a great task for you and your companions.
'Our assault on the fortress of Dol Guldur is drawing near to its conclusion, and I am striving to organize a tactical strike to swing the campaign in our favour once and for all. This is where you come in, Name.
'I need you and your host of stout warriors to break into the lower section of Barad Guldur and cut off the nearly endless stream of enemy forces -- the army of Dol Guldur. Their captain must be felled, and I believe that the soldiers in his wake will be stopped with him. I wish you luck, my friend. You will need luck and more to succeed in this endeavour, but I have great faith in your skill.'
The Malledhrim have asked you and your companions to enter Barad Guldur in an attempt to strike at the heart of the forces of Dol Guldur.
Once inside, Belvaer has asked you to sever the flow of enemy reinforcements streaming from the tower. Belvaer seems to think that the captain of the guard should be found soon after beginning your ascent of the tower.