Dimensius the All-Devouring

Dimensius calls down meteorites on the platform that land one after the other. They kill anyone on impact.

The impact also launches a shockwave across the room that deals heavy damage to players hit and take 300% more damage for 3s from other shockwaves.

Run around the platform to cross a shockwave early, then lose the vulnerability before crossing the next.

Similar to P1:

At 100 Energy, Dimensius channels for 5 s, dealing heavy raid damage. He pulls towards him the raid, the stars, black holes and draws closer his Accretion Disk.

Players inside the Gravity Well (circle) of a star when the cast finishes survive.

Then the stars draw back and continue orbiting the boss.

When he's no longer stunned, Dimensius starts a 10s channel that calls down 8 stars on the platform.

Stars kill anyone they hit upon landing and deal heavy raid-wide damage.

The stars start orbiting around the boss on the edges of the platform. 

The stars are essential to survive when the boss tries to Devour the raid.

At the end of the flying section, there are 2 platforms. There is 1 mini boss on each. 

Divide the raid in 2. Each half lands on their designated platform and kills the mini boss.

Players who collected Stellar Cores deal heavy damage to the mini boss on their platform.

Shortly after landing, Dimensius starts a 32s channel. If both mini bosses aren't dead before it completes, the raid dies.

Dimensius throws an asteroid on the adds' platforms that kills anyone hit.

Quickly choose and kill a Voidwarden from a wall to get to a safe section and dodge.

Unique ability of Pargoth, the mini boss of the right platform:

Casts an explosion that deals damage to anyone hit.

Black holes in space.

Instant Spaghettification on contact. Satisfaction guaranteed or get your money back!

Giant moving laser beam that tears through the entire dimension.

If you get too close to it, you die.

At the start of the phase, Xal'atath buffs the raid with Soaring Reshii, allowing you to get on your flying mount.

Refresh this buff during the phase by going through the gates Xal'atath spawns on the way.

If you lose the buff, you die instantly.

Massive Physical and Magic attack on the tank that also hits anyone within 20 yds. Leaves a 100% Physical damage taken vulnerability for 50s on the tank. Tank swap after each.

This attack also launches a shockwave that deals damage and knocks back all other players.

It also summons adds.

At 100 Energy, Dimensius channels for 5s, dealing heavy raid damage. When it finishes, he devours the raid.

Players with Excess Mass must stack together to create a circle of Collective Gravity. Each player with Excess Mass adds 1 stack to the circle.

Players inside a circle with more stacks than Dimensius’s Growing Hunger stacks survive.

Devour absorbs all Living Mass adds and Excess Mass and grants Dimensius 1 stack of Growing Hunger each time.

Dimensius slams the platform with both hands, killing anyone below.

2 giant spheres spawn where the hands smashed the platform that explode after 10s, killing the raid.

Divide the raid in 2. Each half stands next to a sphere to drain it, reducing their size and the strength of the explosion.

The spheres also shoot projectiles that deal heavy damage and stun anyone hit.