This part works by killing any 15 of the vultak's (at least any of them around Hoo'Loh on the ground gave updates) on Strifewind. The quest updates after every kill.
The camp entrance is through a small space in the cliffs, on the west side of strifewind island at ( 128, -22, -594 ) . It is past the small pond/pool of water. Go in and up the climbing wall to your left. The scroll bearer was fairly easy and had to clear a few mobs to get to him.
The instance in this case is the same as usual (there is a separate one later...I'll explain at that point). Clear the zone and kill the named up top. Lead Hoo'loh to the egg. He then tells you to go and speak to Hoo'Loh (he means Hoo'loh in Barren Sky not the one in the Nest).
Note: If Hoo'loh dies you need to leave zone and reset. So, if you are duoing or soloing leave Hoo'loh at entrance and do not hail him. That way you can wipe as many times as you want and not have to reset. When you clear zone enough to get through safely go back and get him.
Scaleborn warriors: you can get updates in the Sanctum of the Scaleborn in Tenebrous Tangle. We killed the warriors in Sanctum and received an update after 7 kills.
Bloodscale Dreadknights: mobs where the ring event is in Palace of the Awakened. Way up top. Took 3 kills for us.
Formless Abominations: These can be found in The Halls of Fate in The Bonemire. Instead of turning right to go to Sothis, turn left in the room with the option. The formless abominations are in a pit at the end of the area. We received an update with the third kill.
Doomwing Skarize Centurions: These are also found in The Halls of Fate. They have a nasty knockback and I tried to corner the mobs as much as possible (tanks back to corner). In fact, many mobs in Halls of Fate have nasty knockback...BEWARE!
Sothis isn't tough in himself. Level 72 dragon 3 up arrows. It's the adds. At the beginning he has untargetable guards around him. Once you agro Sothis they move toward the group slowly. Once they add they ruin your life. BUT they move very slow. To kill them and reduce their threat to your dragon beat down quickly there are potions around Sothis that are lore and each member can pick up.
I pulled the dragon with my bow up top and fought him there. It bought us a minute extra before we had to deal with the adds.
When the adds approach have one member at a time peal off Sothis and chuck their potion at the Add. It kills them instantly and makes for a MUCH easier fight.
He dropped a pair of very, very cool boots that I was lucky enough to win.
Go back to Nest and sneak in an Instance (Blessed Egg) using the disguise Hoo'Loh gives you.
Be careful at this part. The disguise does change you but if you get too close to the mobs in zone they will see through it and agro (quest failed, go back to Hoo'loh for another disguise).
Once you've made it up top and communed with the egg, you will still get failure messages if your disguise is discovered but it will no longer fail the quest and thus can be ignored.