A Far Greater Menace  

This quest requires that you have finished the access quest to The Tombs of Night: Retribution, and completes the two quests you can get from Trelech Stonehome right next to Ytheri Coldtouch. It also requires you to have completed the first quest from Ytheri Coldtouch called Symbols of the Damned.

Talk to Ytheri Coldtouch outside Timber Falls in Nektulos Forest to initiate the quest. When you've got the quest, head to South Qeynos and go into the mage tower, red entrance. Between Aristide Calais and Rune Shimmerstar you will find a large, dark book on the floor. Examine it, and you will get a quest update. If you are a Hand of Marr supporter from Freeport then you can find the book at the Academy in North Freeport at 12.74, -5.97, -134.14 Copy .

Now you run all the way back to Ytheri Coldtouch and talk to her again. She will now ask you to slay the vampire usurper in the caves below. This is actually the vampire named Dryxl T'Rath that you need to kill. Run over the pentagram at -89, -37, 90 Copy , and you will see that he spawns in the room below the pit. Kill him, and you will see his soul rise and float over the floor and behind the door to the vault.

When you killed him you should have gotten your update, and will now need to speak to Ytheri Coldtouch again.