Your many trials against the vampires and their nefarious minions in D'Morte Burial Chambers, The Tombs of Night and The Crypt of T'haen have led you to this point. While undoubtedly the undead nature of vampires will cause trouble to rise again somewhere beneath that accursed cave under Soul Eater Falls, you and your closest allies have been tasked with this final quest by The Hand of Marr. Enter the Barrow Ruins, slay this renegade pack of vampires and transcribe any writings you see that pertain to vampiric existence.
Simply slay everything you see, and examine the interactable pillars. The hellhounds will respawn, however the vampires will not. Once all the steps of the required quest are fulfilled, Varo Z'Kaz should spawn at his location in the middle of the instance. However, if he does not, then walk towards the entrance and then back down. An in-game message should appear in you chat box indicating that Varo Z'Kaz has spawned. Once he is killed it's safe to leave the instance.