Crown of the Cosmos Mythic Boss Guide

Welcome to our Mythic Crown of the Cosmos (Alleria Windrunner) Boss Guide, for The Voidspire Raid. Learn about the Mythic specific fight mechanics and the strategy we recommend to defeat this boss on Mythic difficulty!

This guide focuses on a Mythic strategy, and won’t explain the basics of the fight, so make sure you read through the Heroic version of the guide for this boss if you are unfamiliar with the encounter.

Fight Style: Single Target with Cleave / Multi-DoT moments

Recommended Setup: 2x Tank / 4x Healer / 14x DPS

Required Utilities: Warlock Gateway / Grips

Hero/Lust Usage: Phase 2

Addons: Northern Sky Raid Tools (NSRT)

Mythic Crown of the Cosmos is going to feel very familiar if you’ve done Heroic, because it’s basically the same fight with a few key swaps in pacing and a couple mechanics that actually matter now.

Before you start, talk to your raid and figure out who needs help swapping platforms later. Anyone who can’t reliably jump or move themselves needs a planned grip or rescue, because Phase 3 is not the time to discover that someone’s class has no mobility and they jump down the gap.

Phase 1 plays almost the same as Heroic. Your main goal is still to stack damage on the Sentinels by killing Void Droplets on top of them. Grips are very welcome here because the faster you ramp stacks, the faster this phase becomes a non-issue.

Your kill order is:

• Demair
• Morium
• Vorelus

Right on pull, you want ranged and melee lined up together next to Demair. The reason is Grasp Of Emptiness. If both groups move in the same direction when the Obelisks appear, the beams naturally point away from the raid and you don’t create accidental damage.

This then flows into Void Expulsion. You bait and drop the puddles behind Demair. Next set of Obelisks, you move back the way you came and drop the next Void Expulsion there. This “forward then back” pattern keeps the early space clean and makes the first kill much more stable.

Once Demair dies, take the Warlock gate if you did not get targeted by Void Expulsion or Grasp. Then you repeat the exact same movement pattern on Morium, and then again on Vorelus.

Tank Note: You can swap tanks to the next Sentinel once the current one is around 1% HP. Don’t stand there pretending you’re required to finish the last pixel.

Silverstrike Arrow Timing

This is the part people mess up on Mythic. Hitting Sentinels with Silverstrike Arrow too early resets your stacks, and if your stacks get reset at the wrong time, you just won’t meet the damage requirement because the Sentinels have a lot of HP.

The simple rule to follow is:

• If the Sentinel is 30% HP or lower when the arrows appear, hit it
• If it is above 30%, skip that arrow set and hit it on the next one

Even if you “skip” an arrow set, people should keep hitting the Sentinel until it is basically dead.

Important note for arrow targets: Use a defensive every time you are the arrow target. If you have nothing, call for an external. Without one of them, there is a good chance you will die.

This intermission is the same idea as the second Heroic intermission. You’re rotating and dodging. Only getting hit by every other arrow from the boss. It’s often easier to play slightly further ahead, and avoid trying to get hit by an arrow with orbs very close to catching up to you.

Start at Skull and aim to end at Red when it finishes.

Phase 2 will feel familiar, but it has one extremely important addition, and if you don’t do it right, you’re wasting the entire phase.

At the start of Phase 2, send a small strike team through the gate to the other platform to kill a Rift Simulacrum. This is the only one that shows up during Phase 2, so it’s free value if you handle it immediately. We recommend 4 players with strong single target or multi-dot to be assigned.

On the main platform, the rest of the raid continues the same bait-and-move game from Phase 1:

• Grasp Of Emptiness happens, melee and ranged move the same direction to point beams away
• Then you drop Void Expulsion in a clean spot

After the first bait and move, the phase starts revolving around the most important mechanic in the fight: Silverstrike Arrow, Images, and Energy Control.

Silverstrike Arrow, Images, and Energy Control

When the boss casts Silverstrike Arrow, it spawns two Images of Alleria. The close one fires the arrow.

Hitting the boss with the arrow removes 4 energy. You can hit her twice per set, so 8 energy per set total. This is easily the biggest gain you can create in the entire encounter, and you should treat it like the objective of Phase 2.

The adds still need to be hit by arrows to die, but that becomes easier because you’re already firing two arrows that can also hit the boss. If your stacking is clean, it just happens naturally.

After the arrows fire, the two Images start pulsing ramping raid damage until they get hit by Grasp Of Emptiness beams. So you need to be aiming Obelisk beams into the Images every time, or you will just rot out.

Any of the 3 beams from the obelisk count as hitting it, when you are correctly aimed at your image, it will glow differently (purple) to indicate you’re aimed correctly. Especially for the far one, small movements can shift the beam a lot, and there is a small delay for the visual to change on the Image, so don’t panic and try not to move too much when aiming at them.

Practical Movement for Images

If the close Image spawns ahead of you, move closer to it, then when Obelisks appear, move back toward the previous puddles.

If the close Image spawns behind you, hug the puddle area and move away from Obelisks when they spawn.

This makes it natural for ranged to hit the close Image and melee to hit the far one, without forcing anyone into weird movement. The Images will glow purple once they’re being targeted properly, so you can quickly sanity check if it’s working.

You repeat this Phase 2 “energy control” loop until the boss hits 100 energy or 40% HP, which is the hard push into Phase 3.

Tip: When you reach the end of the first platform, wait for the next Void Expulsion bait, then take the gate over. It keeps puddles tidy and stops you from dragging nonsense across the whole route.

At 100 energy or 40% HP, Alleria flies up and casts Dimensional Slash. This hits melee first, then ranged, so don’t instantly run into the boss the moment she lands. Let the first hit happen, then move in as a unit.

Once the first slash is done, stack on Skull. This is important because it influences where the Simulacrum spawns.

First Tether Set

When the first set of tethers happens, ranged and melee should snap quickly. Use a movement speed boost and a defensive like AMZ or Darkness, plus personals if needed, so nobody randomly falls over.

Everyone else waits for Grasp Of Emptiness, and then you swap platform.

If you are targeted by Grasp:

• Either stay on the old platform until your beams resolve
• Or jump, but stand to the side so you don’t clip people

Once you’re on the new platform:

• Move the boss to the top corner to keep 25 yards away from the adds
• Ranged bait Void Expulsion cleanly
• Ranged plus a bit of melee kill the Sentinel and Simulacrum stacked together

Then you get another Aspect Of The End set. Handle it in the middle, one by one. No need to rush and chain-kill your raid.

The Hardest Platform Swap

Eventually everyone stacks on the edge of a platform, and this is the hardest move in the whole fight. This is where you need real discipline.

You will get three Aspect circles again and you want to use a Warlock gate, but it must be placed so taking the gate does not instantly break the tether. Place the gateway as short as possible from your current platform to the next.

The rule is:

• You take the gateway only when the Devouring Cosmos puddle is already under you, not before.
• Then you break tethers carefully, one by one.
• This overlaps with Grasp, so Grasp targets step to the side and don’t clip the stack.

From there on out, the rest of Phase 3 is basically “play it like Heroic but with more adds”:

• Kill adds
• Pop Aspects one by one
• Swap platforms when Devouring Cosmos forces it

On the last platform, depending on boss HP, you can decide whether you commit to full clean play or just brute force the ending. There are no special new moves at that point, you just execute cleanly and close the fight.