In Sammath Gûl, the chambers of the Necromancer, the most evil of spirits were summoned and sent forth to do Sauron's bidding. One such spirit still remains, locked behind the doors of Sammath Gûl.
This quest will be cancelled if you leave Sammath Gûl before completing it.
Gorothúl lies deep within Sammath Gûl, a chamber of Dol Guldur.
You should defeat Gorothúl and attempt to unlock the doors behind which the spirit Demafaer resides.
Demafaer stands guard within the chambers of the Necromancer.
The great doors are unlocked; you should defeat the great fell spirit, Demafaer, servant of the Necromancer.