Having successfully destroyed the main bastion of the demons and fel orcs in Hellfire Peninsula; Illidan and Lady Vashj head onto the reactivated dimensional gateway that stands nearby to the east. Upon heading to the place of the dimensional gateway; Illidan and Lady Vashj are met by the fearsome and powerful Doomlord that Altruis have told them about. The name of the doomlord is Kazzak, the leader of the demon race of the doom guards. Illidan now begins to speak with Kazzak.

Illidan: "So, doomlord, I would presume that you are also another one of the agents of Kil'jaeden!"

Kazzak: "Yes, we meet at last! I am Kazzak, the Lord of the Doom Guards, and a high commander of the Legion armies! I was sent here by Lord Kil'jaeden to put an end to all of you! The Burning Legion shall once more reign over Outland! All of you shall fall as the flames of doom rises! We destroyed many of your forces, including your best lieutenants! Soon, the rest of you shall die as they did! I issue a challenge to you alone, Illidan Stormrage! Come and face me alone, weakling! Lord Kil'jaeden shall be pleased, as I would claim the honor of killing you by my very own blade!"

Illidan: "Foolish paltry doomlord! I rule over Outland, and I shall not fall to the Legion! You and your masters have no hold over me! A pathetic demon such as you will not defeat me! Let us see how confident you will be once you get a taste my true powers, Kazzak! None may challenge me!"

Kazzak: "Arrogant words! I shall destroy you, just as I did with your petty demon hunter follower!"

Illidan: "Vashj, I need you to reassemble our forces! I will deal with this wretched demon myself!"

Vashj: "Of course, Lord Illidan. I shall get to it then. Do make a short work of him, master."

Right then; Illidan and Kazzak aggressively clash against one another in what ought to be an epic one-on-one fight. Meanwhile, Lady Vashj rallies the surviving naga warriors and assess the army with the summoning of new troops as reinforcements. Back in the solo battle between Illidan and Kazzak; the doomlord proves himself to be not only a tough foe in terms of his strength, but also powerful in magic. Kazzak casts his powerful spell of Firebolt upon Illidan, which hurled a fiery harmful bolt on the demon hunter. The doomlord then casts a magical Frenzy spell upon himself which instantly increases his own speed in attacking and moving. Illidan answers back at Kazzak by sending a bolt of Mana Burn to the doomlord. The demon hunter also engulfs his own body in flames upon casting his Immolation spell. Illidan and Kazzak continue their fierce attacks against one another in terms of both physical combat and magical spells. Illidan uses his ultimate spell of Metamorphosis, which transforms him into a huge dark fiery demon imbued with chaotic power. Kazzak casts a dark spell of Cripple on Illidan, which magically causes his muscles to spasm and quake. However, the magic effect of the Cripple did not last long on the metamorphosed Illidan.

Seeing the full powers of the demon hunter; Kazzak realizes that he underestimated Illidan. With the powerful chaotic demon form of Illidan; the demon hunter easily dominates the doomlord on their one-on-one fight. Kazzak is a very strong and powerful demon as he is the lord of the entire doom guard race, and an elite agent of Kil'jaeden. However, Kazzak is now being overwhelm by the might and power of Illidan. After a time of intense fighting against the demon hunter; Kazzak has become very weak and heavily wounded as he is also drained out of his mana energies due to the spells his cast, and the bolts of Mana Burn he received. Defeat is upon Kazzak, as Illidan has the overall upper hand in their battle. The nearly dying doomlord now stands defenseless against the demon hunter. Illidan delivers a last vicious attack upon Kazzak with his warblades, as a killing strike to the demon. The doomlord Kazzak is now dead. Standing triumphant; Illidan successfully destroys the Lord of the Doom Guard demons, and another high-ranked commander of the Burning Legion. Lady Vashj and her reassembled naga forces approach Illidan upon witnessing his victory.

Vashj: "You did it once again, master! You just vanquished another one of Kil'jaeden's agents!"

Illidan: "Yes. I stand victorious over the foolish doomlord who thought he could defeat me! Now that Kazzak is out of the way; it is time that we finish our mission here, Vashj. Ready our forces, and take all your positions! I need you to cover me while I seal the gate, like how we did before."

Vashj: "Of course, Lord Illidan. Let us get to it then."

Lady Vashj and the rest of the naga army position themselves against the dimensional gateway. Illidan steps upon the mystical dimensional nexus behind the naga forces and starts up channeling his magical powers that will permanently seal the gateway. As Illidan channels his magic, groups of various demons began charging through the gate. Fortunately, Lady Vashj and her naga army are very well prepared against the emerging demons from the gate. Illidan is heavily defended by the entire naga army of Lady Vashj, and is able to fully focus on his channeling spell without any interruption. Illidan eventually finishes channeling his magic, and successfully seals the gateway. The final dimensional gateway that stands on the Hellfire Peninsula has been permanently closed by Illidan. Upon finishing their task; Illidan was suddenly struck once again by another crippling seizure of pain on his chest. The dark curse of the Frostmourne yet continues to affect him, as the pain has become worse than ever. Illidan even falls down to his knees due to the unbearable pain.

Illidan: "Aaaaaarrrrrggghhh! No! This… damned curse! Aarrghh!"

Vashj: "Lord Illidan! Quickly, the master needs help! Let us bring him back to the base at once!"