The Tomb of Kings

You will be assigned automatically after completing "The Key Stones". When you reach the first intersection underground, take the left path. Kill the skeletons and spiders, skeletons of attention last-servants, with a particularly strong attack. Having killed all the enemies, you reach the lever and use it. The next room in the basement area will be completely private well water. You will then fight against the Revenant, which will leave the floor beneath you - knowing their direction of origin, should not be much of a problem.
So move along the corridor, killing all the enemies you encounter. Reached the intersection, go left, past the iron gate, kill all the enemies in the room. Then you reach the lever on the stone pillar in front of the entrance. Pull it. Returning to the central path, proceed forward until you reach the room with the sarcophagus of stone on the right - just before you can even find the first artifact, ie Ethorn's Dignity.
Then continue straight ahead, killing all enemies along the way. There being closer to the next intersection, diverted to the right. Reach such a room completely filled with Revenant. End it to recover Ethorn's Honour, positioned on the stone table in the left room. Back at the intersection, make your way to the next room, where you are going to meet a demon named Xul'Gurath - pretty fast and powerful, when / if he can come to you, we recommend you focus on dodging his blows, therefore, to prefer a heavily defensive to an offensive.
Killed this enemy, you can retrieve the "Ethorn's Fame," located on the stone pedestal in the center of the room. Xardas will appear, talk to him to complete the quest, go to the exit, killing the enemies along the way. Finally you will get 28000 experience points.