Chamber of the Eye

The Chamber of the Eye is the section in the Tomb of Sargeras where the Eye of Sargeras was held. It was sought by Gul'dan and later Illidan Stormrage. When Maiev Shadowsong entered the Chamber, Illidan let the Chamber collapse. Naisha and the rest of the Watchers were presumably crushed.

In the opposite way of the chamber was a corridor to another one where the Scepter of Sargeras was held.

In the RPG
The Chamber of the Eye is the section of Sargeras' tomb that held the avatar of Sargeras and the last remnant of his withered form: the Eye of Sargeras. Demons are particularly prevalent inside the chamber.

Speculation
It may be the Collapse, the section that Illidan collapsed onto Maiev's forces using the Eye of Sargeras, or the Abyssal Throne, due to the presence of naga and collapsed segments.