Alak-Hul, the Darkblade
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Alak-Hul and his consort, Verok, were present at the Hellmouth when Eris Morn and Eriana-3 led their fireteam to assassinate Crota, Son of Oryx. It was Alak-Hul and Verok's spawn that killed the Titan Vell Tarlowe, with the former delivering the killing blow upon his axe.
Following the raid, Alak-Hul and Verok instigated a rebellion against Oryx, but the rebellion was put down. Alak-Hul's motivation was twofold: first, because he felt neglected by Oryx (which was deliberate, as Oryx wanted Alak-Hul to become a "hungering blade"), and second, to appraise himself in the eyes of Verok. Alak-Hul was captured by Oryx's warriors, and the Taken King decreed that Alak-Hul be imprisoned aboard the Dreadnaught, never to see the light again. But after Oryx retreated from the material realm, Eris wanted to make sure Alak-Hul couldn't take over as the "King of the Hive" and to avenge Tarlowe, ordered for his elimination, and so a fireteam went down into his dark cell and killed him.
The fight with Alak-Hul will be deep in his cell, so it will be almost pitch black, limiting one's field of vision. He is armed with an axe. He will appear to vanish from existence only to teleport to another position of the arena after taking a certain amount of damage from ranged weapons; if attacked with a Super or a Sword he will not vanish or teleport. He will summon waves of Thrall at 25% health intervals, with Cursed Thrall being mixed in at the lower amounts. When on low health, Alak-Hul will become enraged and charge his foes down to cut them to bits.