Terrace of the Moon
The Terrace of the Moon is a large section of the Tomb of Sargeras, being the halls of the Sisterhood of Elune. The Sisters of the Moon are fought here on a platform called the Font of Elune. Illidan comments that he has been to this location. He warns the adventurers that the spirits won't be friendly or forgiving to them.
Touching the uncut stone near a small pillar near the Forgotten Approach will cause you to fall through the map. This was later hotfixed to instantly kill the player to prevent sequence breaking.