Altar of Quetz'lun
The Altar of Quetz'lun is a temple within Zul'Drak, dedicated to Quetz'lun, the wind serpent goddess. The area is guarded by elite wind serpents and air reverents.
When the Drakkari began the sacrifices of their loa, in order to fight against the invading Scourge, Quetz'lun created her own private underworld nightmare, right before her physical body was destroyed, in which she dragged all her former worshippers and high priests into, so they would suffer for their betrayal. However, Quetz'lun was unable to pull her prophet in.
Following the war against the Jailer, the brothers Bronzebeard visited the altar and reported that the temple is otherwise intact, and the wind serpents are still present there.[1]
Phasing
Beginning with the quest 
[20-30] Seek the Wind Serpent Goddess, upon entering this region, the character will gain the 
[Ghostly] buff, "leaving their mortal form behind" and going into Quetz'lun's private underworld.
This uses the same graphics transformation as being dead, and works much like the 
[Bash'ir Phasing Device] in that while you have the buff on, you are in the phased environment.
After completing the quest [20-30] One Last Thing, the area phases back to normal.
Altar of Quetz'lun Digsite
The Altar of Quetz'lun subregion (which includes the altar itself and the courtyard in front of it) is a troll archaeology dig site. It should be noted that the elite guards are initially hostile, and become neutral by completing quests relevant to the area. The guards being neutral greatly simplifies surveying in the area.
According to Muradin Bronzebeard, the temple is a place that holds artifacts of the Drakkari for someone brave enough to face the wind serpents that congregate there.[1]
Patch changes
Patch 3.0.2 (2008-10-14): Added.
References
- ^ a b Exploring Azeroth: Northrend, pg. 55
