Raluvh asks you to find out what is going on in the Halls and tells to not to kill any of the Officers you find as you should be able to use a Mutagenic potion you will find to disguise yourself and speak to them.
First, pick up the Large Draconic Key, that on examination is a Doomwing Key, from the top of a chest at ( 137, 10, -133 ) /waypoint 137, 10, -133. You will need this to open the locked door at ( 119, 1, -125 ) /waypoint 119, 1, -125, on your way down to Jin'tiz the Cataloguer.
One (and only one) member of the group must pick this up.
You can either distract Jin'Tiz by destroying an egg in the room behind him (and he will go back and investigate), Destroy the egg by picking up a vial of Volatile fluid from the benches in the main chamber then right click the center egg, or
you can use Soothe on him so that he does not agro when you grab the potion. If he does agro, make sure someone grabs the potion and let the group wipe.
You must all be in his room as the door shuts. Once Septimus is dead, the Transmogrification quest will update, and the person who has the quest will be given a Transmogrification Elixir. That person should drink the potion at which point they will be turned into droag form.
Watcher Ningiza will then spawn in the room and proclaim the Death of the Doom Lord Septimus. Premonitions of Doom should update and the quest will tell everyone to speak to the three officers.
When the person in your group who is now in droag form hails Ningiza, he will proclaim that person as the new commander of the doomwing legion and call all of the warriors to come and pay tribute.
At this point NPC versions of Doom Guard Vimock, Doom Guard Tammuz, Jin'tiz the Cataloger, and Katalkana Steward of the Legion will all come to you. Vimock will take some time to reach you as he has the longest way to go. Each of them will lay a chest before you.
Everyone should hail each of the officers to update Premonitions.