You have been tasked to go to Tempest Keep's Arcatraz satellite and slay Harbinger Skyriss. Return to A'dal at the Terrace of Light in Shattrath City after you have done so.

Chain

Warp-Raider Nesaad → Request for Assistance → Rightful Repossession → An Audience with the Prince → Triangulation Point One → Triangulation Point Two → Full Triangle → Special Delivery to Shattrath City → How to Break Into the Arcatraz → Harbinger of Doom