Please see https://www.wowhead.com/guides/artificer-xymox-encounter-journal-boss-abilities-raid-loot for full information.
Remember that boss from Castle Nathria with the portals and the giant Axe in the middle of the room? Yup .. this is that guy.
Pull boss to the side of the room, with raid loosely spread close to the side to bait traps.
On normal, someone with immunity can clear traps (on heroic, they stay).
Two players marked with yellow arrows for portal. One will always be tank, that should be dropped near the edge of the room, the other to the centre, near the relic.
Small white circles, loosely spread - sparks jump and leave debuff.
Large platform sized circles will one-shot. Use portals to avoid. If relic shows circle going up it means the circle will be large getting smaller - move to centre of room and use portal to outside edge after circle passes it. If relic shows circle going down it means the circle will be getting larger .. stand at edge portal to jump in.
Tank will get "glyph of relocation" debuff. Taunt swap. Massive raid wide damage & then a raid pull to that tank. Tank gets away to allow debuff to drop.
Phase 2 (75% & 50%):
Adds. Tanks pick up one Acolyte (big add) each.
Acolytes need to die before they get to 100% energy.
Interrupt little adds.
When all adds are dead, back to Phase 1.