Use the Brazier of Beckoning to summon forth the spirit of Kormok and slay him. Return to Bodley inside Blackrock Mountain with the Left Piece of Lord Valthalak's Amulet and the Brazier of Beckoning.
Now we have what we need, so it's time to discuss who it is that you'll be summoning.
Kormok was ok for an ogre, right up until he turned to necromancy. After that, things got creepy for just about everyone in the outfit. It was no surprise then when he took his piece of the amulet and returned to his new home, Scholomance.
But even there, or perhaps especially there, he was not safe from the spectral assassins. They slew him right in front of his master, Ras Frostwhisper.
Left Piece of Lord Valthalak's AmuletClassic reference required item
Brazier of BeckoningClassic reference required item