Slay Highlord Omokk, War Master Voone, and Overlord Wyrmthalak. Recover Important Blackrock Documents. Return to Warlord Goretooth in Kargath when the mission has been accomplished.
By order of Warlord Goretooth, the following inhabitants of Blackrock Spire must be destroyed:
The rotund menace, Highlord Omokk.
The cruel and ruthless troll, War Master Voone.
Overlord Wyrmthalak, taskmaster of the lesser city.
You will also be required to return any important documents that you may find.
Succeed and be honored.
Fail and be forgotten.
Warlord Goretooth salutes.
Warlord Goretooth's dull green skin turns a pasty white for a brief moment.
The lowest level that you can should attempt this quest is Level 58. The quest is a 5-man run through Lower Blackrock Spire. The main targets are Highlord Omokk, War Master Voone, and Overlord Wyrmthalak. You must also obtain the Important Blackrock Documents, which spawn randomly in one of four places.
When you enter the instance, walk up the ramp, kill the orcs sitting on either side, and then the patrol. Continue up the ramp again and make a right out of the doorway, killing a second patrol on the way. Near the doorway to the left are two mobs. It's possible to Mind Soothe them and hug the far wall to avoid fighting them. Once out of the S-shaped hallway, you find yourself on a large platform with some Orcs. Instead of fighting them, hug the wall to your right and jump off the edge. You'll see two ledges sticking out of the wall further down, so make sure you aim for these. After reaching the bottom, the next area if full of spiders. Careful pulling and stopping any runners is the key here. After the spiders, make sure you look for the documents by the pile of skulls on the Ogre platform.
Soon afterwards you should run into Overlord Wyrmthalak. Once Wyrmthalak is dead, check for the documents and head back to the previous room that was full of Orcs. Jump down the first crack and Omokk should be nearby. After ridding yourself of Omokk, check for the documents again.
Fight your way out of Omokk's area, continue across the bridge, and jump down the first crack you see. Bijou should be nearby. Fight your way down to the main floor of the Troll area and make sure you take a right at the bottom fork of the ramp down. Hugging the wall should get you to Voone in a total of 6-7 pulls from Bijou. If you have not yet found the documents, they should be near this last boss.
This rather roundabout way will save you some time and prevent a lot of unnecessary fighting.
This quest was a part of the Onyxia's Lair attunement chain.