Tomb of Sargeras is a raid in the World of Warcraft game. The minimum level for this dungeon is 110+. The location of the entrance to Tomb of Sargeras is in the The Broken Shore zone on the continent of The Broken Isles. The raid contains 0 bosses. The end boss of Tomb of Sargeras is Unknown.
Tomb of Sargeras is expected to be the third raid of the Legion expansion to be opened. The raid is expected to be open at the beginning of 2017. The raid information has not yet been released, however the raid information for Nighthold has already been released. It`ll be a multi-sectional raid instance like those that have been released in the past with the LFR version being released weeks after the Normal and Heroic.
If you had undertaken the pre-Broken Isles scenario, you will have seen the entrance to the Tomb of Sargeras where Gul`dan and his Burning Legion prevented you from going any further. Access to the Tomb is not possible as there is no clear path to the dungeon as yet.
The Tomb is where the Avatar of Sargeras, the fallen titan who was beaten by Aegwynn in a battle thousands of years ago on the wastes of Dragonblight. The spirit of Sargeras is still out there in the wastes of Netherspace. The avatar was placed in the Tomb and sent to the bottom of the waters. However, over time and with Gul`dans help, the Tomb has risen. Both the Horde and the Alliance must travel to the Tomb and kill the Kil`Jadeen, the Eradar who was killed perviously in The Sunwell Plateau at the end of World of Warcraft - Burning Crusade.
You probably wondering why you`re fighting Kil`jaeden again, its because the time has changed when you went back in time to Draenor in the last patch. It messed up time and therefore Sunwell Plateau never happened and hopefully the last, they`ll have another boss next time.