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.
Completion
Good work, <name>! Kormok wasn't all that bad for an ogre, at least not while he was still alive, so I hope he gets the rest that he deserves. But, there is more work ahead of us.
Unfortunately, I do not know the location of the one who died with the right piece of the amulet in their possession. But do not fear; in life I was a dabbler in the art of divination, so I have another task for you, which is going to enable us to ferret out the final piece.
Kormok has a dispellable Bone Shield which will absorb damage and return Shadow damage. He also has an AoE Shadowbolt volley and will summon undead minions to help during the fight.
There are two possible strategies:
Have one tank stay on Kormok and then have the damage dealing classes take out the minions that appear. This is slower but safer. You do run the risk of running out of mana.
Concentrate all damage on Kormok and ignore the summoned minions. If you have several high damage classes, then this is a viable strategy. You do run the risk on getting overwhelmed by minions.
Healing should only be performed by priests with Holy Nova or Vampiric Embrace to avoid pulling the attention of the minions.