For the first part of this quest, you are asked to enter The Living Tombs and fill a blessed crystal vial with water from the Pool of Immortality. Head to the top of the big building in the middle of the Trade Court, specifically to ( -635, 3, 158 ) /waypoint -635, 3, 158 and then use the vial that's in your inventory. To get to the Pool of Immortality jump down from the aqueduct that you are on when you enter the tombs and run to the back of the room and go up the ramp at ( -590, -5, 122 ) /waypoint -590, -5, 122 . There is a climbable wall at top of the ramp to the left ( -619, 9, 110 ) /waypoint -619, 9, 110, climb it. Go into the water in the aqueduct turn right and jump off the edge. You are now in the Pool of Immortality. In the pool are level 52 heroic Serpents of Immortality. The pool can only be reached by jumping.
Once that is done, you are told to find someone who may have information about the Ewer of Sul'Dae. You've already been told the Dark Elves of Neriak currently have the item.
The instance is the standard 5 room house layout, and the item you need is downstairs. You can get to this from the right hand room when you zone in, but there is a barrier in the way.
Click the orb ( -4, 9, -35 ) /waypoint -4, 9, -35 upstairs to deactivate the barrier. Be careful, as there is a level 65, heroic, aggro mob next to it.
Once done, go back downstairs, into the right room and down to the bottom floor. You really can't miss the Ewer... it's massive!( 4, -9, -14 ) /waypoint 4, -9, -14. Right-click on it and edge forwards until you're close enough to pour the water into it.