Assist Commander Hobb and the Scryers in defending the Sanctum of the Stars. Once all of the Dragonmaw forces have been defeated, return to Overlord Mor'ghor at Dragonmaw Base Camp with the Scryer Medals.
Take these Scryer medals. Mor'ghor will need proof of "victory" once this is over. He will recognize them as coming from the corpses of fallen Scryer soldiers.
Now all that remains is to use the signal flare to alert the Dragonmaw raiders. We will crush them when you are ready. Just give me the word.