Legend of Edda News & Events & Guides

In the antechamber, you must go off to the left wing and kill the Iron Council to open the door to the rest of the instance. After that door opens you must kill Kologarn to actually cross the path into the rest of the instance.

From here, the raid is fairly non-linear. You have your choice between Auriya, Mimiron, Freya, Thorim, and Hodir. However, you must kill all of them to access the Decent into Madness.

Down into the decent, you encounter General Vezax, who is blocking the loe gold where Yogg-Saron lies in his prison.

As far as the completely optional boss, Algalon the Observer, who you can find in a wing to the right of the antechamber, you must kill all 4 hard modes of the watchers, Hodir, Thorim, Freya, Mimiron, to even open the door to his room.

Hope this helps.