Skull Rock is the 2nd quest in the Margoz quest chain.
Gather Searing Collars from the cultists in Skull Rock.
Bring them to Margoz at his camp.
<name>. The Burning Blade has infested the cave east of Orgrimmar known as Skull Rock. Inside that cave they perform vile rituals, and burn their own flesh with Searing Collars.
By wearing these collars, I believe the cultists attune themselves to demonic power. But to confirm this, I must have a collection of the collars to study.
Go to Skull Rock and gather Searing Collars from the cultists you find there. Bring them to me, and I will uncover their secrets.
Have you yet entered Skull Rock, <name>? Do you have the Searing Collars?
Good. Hiding within these collars is the secret behind the Burning Blade. And I will uncover that secret...
Upon completion of this quest you will gain:
- 900 XP (or 5 40 at level 70)
You will need one inventory spot open to retrieve the 6 Searing Collars, which are required to complete this quest, from the corpses of the Searing Blade Orcs.
You may wish to complete this quest along with the first of the  quests, as both require you to enter this cave. You may also wish to find and kill a Searing Blade Orc named Gazz'uz and retrieve the Eye of Burning Shadow from his corpse. This item will allow one to receive the  quest.
If you are a Shaman doing the  quest and you need to get a Reagent Pouch from a Burning Blade warlock, it's important that you know this is NOT the cave you will get it from. There is another cavern occupied by the Burning Blade clan roughly southwest of Skull Rock, and THAT is the one where the warlocks drop the pouches you need. The cave can only be approached from the south, since it's on high ground and trying to approach it from the north will result in you running into a high cliff wall you cannot climb. More than one person has tried to get the pouch from the cave at Skull Rock without success.