On Mythic, Rygelon will apply 3x Dark Eclipse debuffs at a time. Players with this debuff need to run into the Collapsing Quasar Field created by killing a Collapsing Quasar before their debuff expires. You have 12s to run into the puddle once the Quasar has died.
Most guilds use a weakaura to assign players to puddles on either the left or the right, so that players don’t try and steal each other’s puddles.
On Mythic you only get one spare Quasar, meaning that you can only have 1 player "steal" a cleansing puddle per wave or you will wipe the raid.
When players enter the Collapsing Quasar Field to cleanse their debuffs, they will also cause AoE damage to the raid, especially important with the first 3 as most strategies send in the first 3 players at the same time, causing a lot of raid damage.
If someone misses it, when their debuff expires they will deal 112K shadow to the entire raid. This damage is survivable with some personal defensives/big raid defence cooldowns but it should be avoided at all costs.
The boss will cast Celestial Collapse, spawning 6 Collapsing Quasars that will attempt to reach him.
These need to be controlled so that they die with the correct cadence alongside the Dark Eclipse debuffs you need to manage.
Once killed, the Quasars will leave a bomb on the ground inside The Singularity called an Unstable Quasar, which will explode after 3 seconds when someone walks over it.
These can be problematic if you kill the Quasars too close to each other both positionally and in terms of when they die, as someone going inside through a puddle could be met with a previous players’ Unstable Quasar explosion in their faces. To avoid this, kill them away from each other and stagger the deaths between pairs so that this doesn’t happen.
The Quasars will gradually become less and less susceptible to slows etc through Accretion but this is not usually a factor that needs considering too much.
I will cover how to control the Quasars and kill them in the strategy section.
The boss will spawn Cores that need to be soaked in sets of 3. These will be randomly placed around the room, there is generally always one close to melee, a mid-range one, and one further towards the back of the room - sometimes they are far to the left or right.
We assigned soakers based on their distance from the boss - so 1 player assigned to melee, 1 assigned to mid-range, and 1 assigned to furthest.
Players who soak these Cores will take damage from Cosmic Ejection and also receive the Cosmic Irregularity debuff - one player can soak a core they will never die to having more than 6 stacks. These players will take a lot of damage and need to use defensives while soaking.
Healers and tanks are the ideal candidates to soak cores as they cannot get the Dark Eclipse debuff, so you should assign all 5 healers, and both tanks, leaving you with 2 ranged dps players who need to also be assigned (recommend warlocks).
If the warlocks get Dark Eclipse while soaking they can generally just leave and the core will hit someone else for a tick or two but it shouldn’t cause any huge problems.
Dodge the lines, getting hit isn’t a 1-shot if you’re healthy but your healers will hate you for it.
Tank swap mechanic, same as Heroic.
When the boss reaches full energy he will cast Massive Bang, same as heroic.
The main difference here between mythic and heroic is that you cannot attack and kill the Unstable Matter to create the protective Unstable Matter Fields you need to stand in to survive Massive Bang. Only players who have Event Horizon will be able to do this.
Inside The Singularity there will be 3x Unstable Cores that need soaking through Stellar Decay. There should be one close to where the melee entered the phase, one close to the Ranged, and one at the back of the room.
Players should all be soaking at all times unless dropping a Dark Quasar away from the group. Melee soak their Core, Ranged theirs, and then both groups should converge on the 3rd Core and soak it before they run out of time and the boss casts Shatter Sphere.
When the cores die they will cast Gravitational Collapse which needs to be soaked by the tanks.
Quasar Wave 1:
When the first Quasars spawn, have 2x Boomkins stood next to the mid-range Quasars, and have a Priest use Shining Force on them to knock them towards the boss.
Cleave down all 4 around the boss and then send in the first set of 3 Dark Eclipse debuffed players.
These players need to hit the Unstable Matter, especially important for the first cycle of the fight as you have not gotten any cleave damage onto this Matter whilst in the Intermission.
Slow the back 2 and let them drift in towards the boss, killing them by the time the next Dark Eclipse debuffs are about to come out, and have the Ranged players walk in here.
During this time you need to make sure the Cosmic Cores are being soaked.
Have a shaman keep Earthbind Totem up in the centre of the room to keep the Quasars slowed - using the conduit allows for enough uptime.
Quasar Wave 2:
Nuke the 2 in melee very quickly and have melee walk into these puddles.
Have your Boomkins knock the mid-range ones back with Typhoon, and warlocks slow the back ones with Curse of Exhaustion. You need to try and keep the mid-range ones separated from the back ones as best you can here - Ring of Peace can be really good for splitting these up once the mid ones are on knockback Diminishing Returns from the Typhoon you can safely place it to knock the back ones only.
Then kill the last 2 for ranged 3 seconds after the melee have gone in - once again these players should attack the Matter if it isn’t already dead.
Go to assigned positions for Massive Bang, making sure not to steal people’s spots.
Once inside, use personal defensive cooldowns whilst soaking the Unstable Cores, and move straight to the 3rd core once your initial core starts casting Gravitational Collapse.
Drag the boss to the 3rd core briefly, and then over to the next Unstable Matter to get some free cleave on it before the next phase.
From this point the rest of the fight is rinse and repeat with gradually increasing raid damage due to Eternal Radiation.