Naxxanar

Naxxanar is a nerubian Scourge necropolis floating above the Temple City of En'kilah in the Borean Tundra. During the war against the Lich King, Naxxanar was the command post for the Scourge in the Borean Tundra, run by Prince Valanar, the overlord at the time.

Both the Alliance and Horde sent adventurers to Naxxanar. To enter they needed to kill High Priest Andorath, High Priest Naferset and High Priest Talet-Kha, and after gathering their scrolls, they received the keywords "Shabtir bakh sokhen". At the behest of Chieftain Wintergale of Taunka'le Village, the adventurers found Valanar in the inner chamber of Naxxanar with his lieutenants, Vanthryn the Merciless and Luthion the Vile.

It was here the brave death knight Thassarian faced off with Prince Valanar and discovered that he'd been trying to destroy the Valiance Expedition from within by masquerading as Counselor Talbot. Valanar had Thassarian's sister, Leryssa, and General Arlos under mind control and was about to hand them over to the Lich King. Thassarian defeated Valanar to save both of them.

Following the war against the Jailer, the brothers Bronzebeard reported that Naxxanar still floats over En'kilah, but there doesn’t seem to be much going on there anymore.

• When the Blood Prince Council is engaged in Icecrown Citadel, Prince Valanar says "Naxxanar was merely a setback!"