The Chamber of the Dreamer is located inside the Temple of Atal'Hakkar. It is located through the southern tunnel from the Pit of Sacrifice, and is the location of the sleeping Shade of Eranikus. In order to enter defeat this dragon, one must first kill Gasher, Hukku, Loro, Mijan, Zolo, and Zul'Lor, who stand on the six ledges overlooking the Pit of Sacrifice. These mini-bosses can only be reached by going through the Hall of the Cursed.
After defeating these mini-bosses, the shield protecting the Lair of the Chosen (east of the Pit of Sacrifice) will vanish. Adventurers must then defeat Jammal'an the Prophet and Ogom the Wretched, as well as several Atal'ai subordinates, who must all be killed before facing the two bosses. The death of Jammal'an lets one face the Shade of Eranikus.
In addition, any and all dragonkin in and around the Pit of Sacrifice must be killed before battling the Shade of Eranikus, as he will summon any of them left alive to his aid during the fight.