How I got to xyor because I'm getting allot of questions I'll explain my experience. Upon getting to phogoth we cleared out the room of all ads. Then walked in front of the boss to start encounter. Walked ledges killing ads for about 15 minutes until xyor spawned. Everybody in our party did have the legendary quest and everybody in our party was level 26 or higher. We found it easiest to take out most of the ads with a sniper rifle of the color shield they were wearing. I think we got about another 4 or 5 waves in before xyor spawned. By the time he spawned phogotha was about 50%.