After learning Draconic you can talk to Lord Nagafen, which is more easily done than last time by selecting the "Deserted" instance of the Oratorium and walking straight on to his lair.
When you hail Lord Nagafen make sure you are standing very close to him or you won't get it the dialogue to begin.
Also, you may run into a bug with the quest dialog (ie: when you hail Nagafen he says something but does not start a dialog). Simply re-log your character and the issue may correct itself. Stepping up on his platform (to get closer) may also work.
Be careful, If you anger Lord Nagafen, He will hit you for 400k. This will kill anyone around level 50 immediately, so be respectful.
Nagafen will tell you that you need to revive the ice dragon Lady Vox (Spirit of Vox). To do so you need to recover some essences which are being held by three drakota. These drakotas are level 52x4.
Revive Lady Vox in The Crypt of Vox, entered via the large doors above the platform in the first room (past the doors) of Permafrost. To revive her, you need to have someone on the quest examine the essences in your inventory in the following order:
Essence Shard of Soul
Essence Shard of Heart
Essence Shard of Mind
After entering in the essences, click the totem in the room.
Note: Clicking the totem will kill the person that does it, and also set the lockout timer. There is no revive point in the zone so make sure they can be resurrected. If soloing, you can use a Scroll of Resurrection.
If the totem is clicked prior to using the essences, an aggro Lady Vox will spawn and your party must then re-enter the zone in order to restart the sequence.
After reviving Lady Vox, hail her standing underneath to get your quest advancement.
Note: if you are very high level and kill Drayek too fast, you will break the encounter and be stuck on this step until the instance becomes resettable (a bit over 2 days)! You can try /tar King and sometimes be able to recover him.
Note 2: At lev 93 and mentored to lev 55, full gear for 93 with my familiar, diety pet, Zelniak and my merc, I was able to complete the quest without a problem.