Leah: The guards were asking you about this... Black Soulstone. I remember reading about it in Uncle's journal, but it didn't seem important.
Adria: Oh, but it is. It is the key to defeating evil forever! It was created by the mage Zoltun Kulle to trap demonic souls.
Leah: Yes! He was a renegade Horadrim, dismembered by his brethren before he could activate the soulstone. His head was sealed away in the Dahlgur Oasis.
Adria: We must retrieve it, because if we're to use the soulstone to defeat Belial and Azmodan, Zoltun Kulle must live again!
Templar: I do not like this. We can defeat Belial without using a wizard's foul magic.
Necromancer: I have a new ally... the witch, Adria.
She believes that the Black Soulstone will allow us to defeat the Lords of Hell. But this remains to be seen...
Find the oasis gate in the Flooded Causeway beneath the Caldeum Bazaar
Dealing with Zoltun Kulle seems like a foolish notion, but the Black Soulstone is the best possible prison for Belial. For if we killed him, he would be reborn again in time. There is no true death for the Lords of Hell.
LOCATION: CALDEUM BAZAAR
Note: Exit the Hidden Camp to the Caldeum Bazaar. There, make a left turn, then another left turn. Enter the Flooded Causeway through the sewer manhole.
Talk to Emperor Hakan II in the Flooded Causeway
LOCATION: FLOODED CAUSEWAY
Templar: It's quite a maze down here, isn't it?
Emperor Hakan II: Listen to me. I cannot talk for long. Belial's guards are constantly watching me!
Necromancer: Are they?
Emperor Hakan II: Forgive me for my behavior at court. The guards would have killed me had I sided with you. But I will help you now as I can.
Find Dahlgur Oasis through the Ruined Cistern beneath the Caldeum Bazaar
Emperor Hakan claims that he is sympathetic to my cause, but I do not believe hm. What ordinary child would sneak into the sewers precisely when I am leaving? I will watch him closely.
Emperor Hakan II: You must be headed to the oasis. I can open this gate for you.
Note: Exit through the Ruined Cistern.
Note: There is a chance to find a Cain's Lost Satchel that drops this:
Note: Exit the Ruined Cistern through the Path to the Oasis.
Find and enter the Forgotten Ruins in Dahlgur Oasis
You will find the Path to the Oasis Waypoint right after clicking the exit. Unlock it.
Templar: By the Light... I've never seen a place like this.
Note: There is a chance to encounter Sokahr the Keywarden of Putridness in this area. He drops the Infernal Machine of Putridness for the Hellfire Amulet.
Templar: Brast, one of the historians of my order once came here. He called it a "fertile valley of slender trees and bold flowers. A place where evil has not found root."
Note: Explore to find the Dahlgur Oasis Waypoint if you haven't unlocked it yet.
Necromancer: Traces of Zoltun Kulle's magic linger here...
Find Zoltun Kulle's Head in the Forgotten Ruins beneath Dahlgur Oasis.
Templar: Brast never wrote about this!
Note: You might find in this area Hunter's Journal:
Get Zoltun Kulle's Head (0/1)
The Head of Zoltun Kulle...
Note: The head drops a journal. Pick it up.
An Ancient Guardian spawns shortly after looting Zoltun Kulle's head.
Return to Adria in the Hidden Camp with Zoltun Kulle's Head
I have retrieved Zoltun Kulle's head. The mad wizard's spirit still dwells within it, but he cannot awaken without help. Should things go awry, I suppose I could use him as a new phylactery.
Note: Use the Town Portal (T).
LOCATION: HIDDEN CAMP
Adria: If you keep holding back, then you'll never improve.
Adria: Leah, are you all right?
Leah: Yes... I think so.
Adria: I'm sorry to push you like this, but it will all be for the best in the end.
Leah: I know.
Note: As you approach Adria, there is a journal on the ground:
Adria: It is time. Leah, cast the spell as I taught you!
Zoltun Kulle: I live again!
Tyrael: Zoltun Kulle. We need you to activate the Black Soulstone. We would use it to trap the last two Lords of Hell!
Zoltun Kulle: I know your voice, stranger. It has haunted me in death, just as it commanded me in life. Tyrael!
Tyrael: I am. But now mortal.
Zoltun Kulle: Ah... Fate is... whimsical.
NEXT QUEST: BLOOD AND SAND
TOWNSFOLK DIALOGUES: HIDDEN CAMP
Note: After finding Zoltun Kulle's Head, this dialogue is unlocked. This is the last time Kala appears in the Hidden Camp.
Note: These dialogues are unlocked after turning in the quest.
TOWNSFOLK DIALOGUES: CALDEUM BAZAAR
Note: These dialogues are unlocked after returning to the Hidden Camp from finding Zoltun Kulle's head.
Noblewoman: You can't treat me like this, like... like some commoner!
Note: This dialogue is unlocked after turning in the quest.