Stardouser

Quest giver: Telivar S`Vik
Requirements: Meeting Adjorned
Request Phrase: more of us
Entry Phrase: ready
Reward: Chronobines, Timeshear Black Fragment Dena

You'll need to clear the area and say "Telivar" to spawn him to request the mission. You can bring 2 groups, however all mercenaries are despawned when you enter.

The goal for the mission is to simply kill Stardouser. The intended strategy is to look at him and see a blue light that paths from him to one of the portals. If you go to the portal you can tell either riftseeker "switch" (must be sneaking) to turn the portal off, this stops mobs from spawning from it and going to assist the Stardouser, but you might get one when the switch happens. Return to him and repeat the process until you don't see any more blue lights, then kill off any "hunter" adds which had spawned, the kill Stardouser

It hits for 10k, has AE rampage, casts an AE stun/blind, and a targeted AE snare, stun, 2k dot, attack debuff, and mana dot.

Since he has low health a more direct approach is possible: ignore the portals, charge him, and kill him ASAP. With enough dps you can get him dead before adds are an issue.