Long ago, before the fall of Neriak there was a very powerful necromancer. He found a way to steal the souls of not just the dead, but the living as well. He fed on every living and dead thing within his grasp, until there was nothing left but his own people. The streets of Neriak slowly began to empty. The great dark elf army's numbers dwindled as the Necromancer dined on everyone and everything. His hunger could not be contained. The many mages of the dark elves figured out what was happening and joined together. Using all of their combined power they buried the Necromancer's lair far below the earth.
[Recently] we have received reports that the The Thexians, in their misguided attempts at power, have disturbed Fallen Gate, that wretched evil place. [It] has been excavated and it seems several artifacts of this Necromancer were looted by the Thexians. They are using them to join and raise the Necromancer. I cannot let this happen.
The final boss T'Sarn V'Thal gives achievement experience. To summon him, kill the four profane harbingers guarding the inner perimeter of the central chamber, then kill the four dark elf minions surrounding the central sarcophagus. His chamber is located at ( 58, -46, -112 ) /waypoint 58, -46, -112.