Driven by greed, Xy'mox lead his most loyal associates to the Sepulcher of the First Ones. Using the chaos to plunder its riches, Xymox seeks to weaponize ephemera in order propel himself to unlimited power.
This fight is a three phase encounter with intermissions at 75% and 50%.
The main mechanics of this fight are the 
Genesis Rings and 
Dimensional Tear. You will make use of the Dimensional Tear portals to avoid being hit by the Genesis Rings.
Additionally the tank mechanic 
Glyph of Relocation will grip the entire raid to their location. Be mindful to not get gripped through Rings or Traps as they will trigger!
Genesis Rings - Make use of the Dimensional Tear portals to avoid being hit by the Genesis Rings.
Rings can come from the inside and move towards the edge. Indicated by the ring going down the relic in the middle.
Rings can also come from the outside and move towards the middle. Indicated by the ring going up the relic in the middle.
Dimensional Tear - Two debuffs will be applied to a tank and a random non-tank player. One should go to the middle of the room and one to the edge.
Glyph of Relocation - Tank debuff when boss reaches full energy. Does drop off damage to the raid and grips the entire raid to the tank.
Anything that the raid gets gripped through activates (Traps, Portals, Rings). Example of gripping through portal:
Hyperlight Sparknova - Spread when this debuff is active to avoid cleaving other players.
Stasis Trap - If you walk into one you will be stunned and need to be broken out.
[Heroic/Mythic][Continuum Stasis Trap - On these difficulties the stasis traps transform into Continuum Stasis Trap. They act the same when a player runs into one, however the key change to this mechanic is that they will no longer dissapear once armed. They will instead re-activate after 3 seconds.
When you reach 30% new portals will go out and the boss will now create Genesis Rings in sets of 3.
If you are currently dealing with Rings this phase will be delayed until the Rings are over.
Artificer Xy'Mox Swing Timer: 1.5s (Curse of Weakness 1.8s)
Xy Acolyte Swing Timer: 1.5s (Curse of Weakness 1.8s)
Leg Sweep can be used to stop the Xy Spellslingers from casting during the intermissions.
Ring of Peace can be used to move the Xy Spellslingers in the intermissions.
Transcendence can be useful to get yourself over the rings where you have a debuff overlap.
Zen Meditation should be used if you need to run through a ring. Be mindful of the very wide hitbox, you may be hit multiple times.
Fiery Brand should be available for every Glyph of Relocation.
Sigil of Chains can be used to grip all of the adds in the intermisison together for better cleave.
Sigil of Misery can be used to stop a cast from the Xy Spellslingers in the intermissions.
Sigil of Silence can be used to help move the Xy Spellslingers in the intermissions.
Divine Shield and 
Blessing of Spellwarding will allow you to run through the Genesis Rings without taking damage. This will allow you to position more agressively on overlaps with Glyph of Relocation.
Spell Reflection can be used to reflect the casts from the Xy Spellslingers in the intermission.
Spell Reflection should be used to mitigate the damage from Glyph of Relocation.
Rallying Cry is best used where Glyphs are on your co-tank to help the raid survive.
Stampeding Roar is useful to help the raid move from Genesis Rings and Hyperlight Sparknovas.
Anti-Magic Shell will allow you to run through the Genesis Rings without taking lethal damage. This will allow you to position more agressively on overlaps with Glyph of Relocation.
Anti-Magic Zone is best used where Glyphs are on your co-tank to help the raid survive.
Gorefriend's Grasp & 
Abomination Limb are useful to group everything together in the intermissions.
This fight is a four phase encounter with intermissions at 75% and 50%.
The main mechanics of this fight are the Genesis Rings and Dimensional Tear. You will make use of the Dimensional Tear portals to avoid being hit by the Genesis Rings.
Additionally the tank mechanic Glyph of Relocation will grip the entire raid to their location. Be mindful to not get gripped through Rings or Traps as they will trigger!
Bloodlust/Time Warp/Heroism is best used in the Final Boss Burn (30%).
Before you pull this boss you should establish where you will place the Dimensional Tear portals.
I would recommend that Tanks go to the middle always and the non-tank player moves towards the edge.
RaidPlan Link for the sample movement plan below.
The concept here is for Heroic as you're more limited on space. You will want to move around the room clockwise dropping traps behind you.
Dimensional Tear portals should be placed ahead (but not too far ahead!) of where the Ranged clump of players are so that they are not having to run a marathon every 30 seconds for rings.
If you have a Protection Paladin, Blood Death Knight, Brewmaster Monk or have them take the first Glyph of Relocation in Phase 2 (75%-50%) as during PTR testing this ALWAYS overlapped with rings. All three of those tanks can go through a ring without issue (Spellward/Divine Shield/AMS/Transcendence/Door of Shadows).
Genesis Rings - The boss will channel into the relic in the centre of the room every ~30 seconds. When this cast happens pay attention to the direction that the ring is moving on the relic as this indicates where the rings will come from.
The boss will only create 1 ring per cast in Phase 1 & 2 (100-50%), he will create 2 rings per cast in Phase 3 (50-30%), and will create 3 rings per cast in Phase 4 (30%-0%).
You can get the same pattern repeating. Don't asume that it will be alternating each time in Phase 3 & 4.
If the ring is moving down the relic, then the ring will come from the inside and move towards the edge.
If the ring is moving up the relic then the ring will come from the outside and move towards the middle.
Dimensional Tear - Two debuffs will be applied to a tank and a random non-tank player. One should go to the middle of the room and one to the edge.
Glyph of Relocation - Tank debuff when boss reaches full energy. Does drop off damage to the raid and grips the entire raid to the tank.
Anything that the raid gets gripped through activates. Traps will activate. You will take damage from Rings. You can be gripped through Portals. Be mindful of your positioning as a raid.
There are moments where the Glyph and the Rings are both happening at the same time. During this scenario the Tank will have three options:
1) Use an immunity/heavy damage reduction to run through the Ring so that the raid can be gripped after they go through the Portal.
2) Stand on the raid and utilise raid defensive cooldowns.
3) Grip the raid through a portal to safety.
All three options have their purpose. However, for any to work, COMMUNICATION IS KEY! This is especially true for gripping the raid through a portal as people need to be positioned correctly so that they get gripped correctly.
Example of gripping through portal:
Hyperlight Sparknova - A small circle is placed around every player in the raid. Spread when this debuff is active to avoid cleaving other players.
Stasis Trap - If you walk into one you will be stunned and take Arcane damage every 2 seconds. Other players will need to kill the trap to break you out.
[Heroic/Mythic][Continuum Stasis Trap - On these difficulties the stasis traps transform into Continuum Stasis Trap. They act the same when a player runs into one, however the key change to this mechanic is that they will no longer dissapear once armed. They will instead re-activate after 3 seconds.
Be mindful of your raid positioning on Heroic/Mythic as bad trap placement can mean that you run out of room if the fight goes on.
When you reach 30% new portals will go out and the boss will now create Genesis Rings in sets of 3.
If you are currently dealing with Rings this phase will be delayed until the Rings are over.
When you enter this Phase you will have a prolonged period where the boss is setting up the mechanics for the Phase (new Wormholes, Hyperlight Spark etc) and this is the time to get as much damage on the boss as possible as once the Rings begin, you won't have much time to hit the boss and you just need to survive.
The fight flow from this point is that you will handle the rings as they come out and you will then have a short reprieve to deal damage to the boss and repeat.
Artificer Xy'Mox Swing Timer: 1.5s (Curse of Weakness 1.8s)
Xy Acolyte Swing Timer: 1.5s (Curse of Weakness 1.8s)
Leg Sweep can be used to stop the Xy Spellslingers from casting during the intermissions.
Ring of Peace can be used to move the Xy Spellslingers in the intermissions.
Transcendence can be useful to get yourself over the rings where you have a debuff overlap.
Zen Meditation should be used if you need to run through a ring. Be mindful of the very wide hitbox, you may be hit multiple times.
Fiery Brand should be available for every Glyph of Relocation.
Sigil of Chains can be used to grip all of the adds in the intermisison together for better cleave.
Sigil of Misery can be used to stop a cast from the Xy Spellslingers in the intermissions.
Sigil of Silence can be used to help move the Xy Spellslingers in the intermissions.
Divine Shield and Blessing of Spellwarding will allow you to run through the Genesis Rings without taking damage. This will allow you to position more agressively on overlaps with Glyph of Relocation.
Spell Reflection can be used to reflect the casts from the Xy Spellslingers in the intermission.
Spell Reflection should be used to mitigate the damage from Glyph of Relocation.
Rallying Cry is best used where Glyphs are on your co-tank to help the raid survive.
Stampeding Roar is useful to help the raid move from Genesis Rings and Hyperlight Sparknovas.
Anti-Magic Shell will allow you to run through the Genesis Rings without taking lethal damage. This will allow you to position more agressively on overlaps with Glyph of Relocation.
Anti-Magic Zone is best used where Glyphs are on your co-tank to help the raid survive.
Gorefriend's Grasp & Abomination Limb are useful to group everything together in the intermissions.