People have made so many mistakes trying to explain Xylar. Xylar is a raid boss that can only be triggered if you kill Atheon in EXACTLY 69 seconds after he spawned. One you fight Xylar, 2 people from your fireteam will be randomly teleported into a tunnel where they have to search for 6 switches and turn them on in order to open a door at the end of the tunnel. While the rest of the 4 fight waves and waves of thralls that trigger curse thrall explosions (but disguised as regular thralls) Once the two in the tunnel go through the door, they return and then you can damage Xylar, then when Xylar is at 25% health, 2 huge meteors slowly come down at your team, you must shoot at these will all your might, when the meteors are destroyed, a 2 relic shields appears in the center, once grabbed, the relic holders must kill 3 goblins labels as "Xylar's Disciple", once the relics have super, you must both shoot Xylar at the SAME time, then when Xylar is down... Xylar appears again with 50% more health and you must do everything again, but the meteors will come down much faster and Xylar will still shoot you VERY fast. You guys need to be quick on your feet. The thralls will come at you with 3x the speed and MUCH bigger explosions. Hope this helps! Edit: you people need to know lore, if you knew, you'd know how Xylar got thralls. ~[i]TheGreatNike[/i]