Cathedral of Eternal Night Mythic+ Guide

Instance Breakdown

Recommended Comp for high keys: You should bring at least two AoE stuns to Cathedral to ensure the trash goes smoothly.
Highest Tyrannical key done in time: 20
Highest Fortified key done in time: 21
Instance Timer: 35:00
Average # Mobs per pack: 2.9

 

Trash

Click the arrows to navigate through the trash path.

You can pull these two packs together most of the time. The Destroyers need to be stunned / interrupted to take care of Shadow Wall (a giant defensive ability) and your party should spread out to minimize damage taken from Fel Strike which hits in a line.
Dul'Zak will trigger when you walk slightly down the path. He's harmless except for Shadow Wave which will target a random area and then murder everyone inside it a few seconds later. Strafe around so that you're behind him to avoid it. 

Dul'Zak will actually run around the entire platform and then fly back to his starting point if you let him run past you. This isn't useful information, but I thought you should know.
The Stalker is alone, but can be pulled with the patrol. The Felbringers drop a giant green bubble that will give you a haste buff if you stand inside. Kill this mob last to maximise the number of bubbles you can take advantage of. You can also pull the patrol if Dul'zak to take advantage of the haste buff there, though this is riskier.
Walk around the inside of the pillar to avoid the Dreadwing pack. They aren't that dangerous, but it's still unnecessary trash that's easily skipped. You can fall to your death, so take a bit of care.
The Soulmenders cast Demonic Mending which is a nasty AoE heal. You've got 3 seconds to interrupt it.
Priority is: Move mobs out of haste bubble > Interrupt Demonic Mending > Interrupt Shadow Wall.
This is actually a nasty pack and you might benefit from pulling them downstairs to a more open area. You need to interrupt Alluring Aroma since a bad Mind Control is a wipe.
Skip the Vilebark Walker patrol by jumping over the flower bed.
Run away from the Stranglevine Lasher if targeted by Choking Vines. Be careful not to run back into the patrol we skipped. Interrupt Fel Rejuvenation and don't stand in any green circles. You can pull the Hellblaze Temptress with any of the other packs.
The Vilebark walker must be stunned during his Lumbering Crash cast - it'll one shot your party on higher keys.
Skip the patrol by jumping over the flowers. If you end up pulling it then just kill it at the base of the stairs.
Pull the Hellblaze Imps on the right hand side along with the two that bounce from side to side. Don't let them get a cast off if possible.
You need to clear every pack here, preferably before you pull Gazerax since the boss spawn is tied to his death. The Scavengers will throw random books around you which will begin to cast spells. You can stun the spell and then just cleave them down - they won't start a new cast. You can pull more than one pack at once, but you'll need to keep them locked down since both mob types are quite dangerous if left to free cast.
Gazerax has a couple spells that we need to be very familiar with (in order of importance):
- Blinding Glare: Long cast time, then instant death to anyone facing him.
- Focused Destruction: Heavy AoE damage to the party over six seconds. Have your healer cooldowns ready.
- Fel Glare: Easily avoidable swirls on the ground.

The boss will crash down in the middle after he dies. Give him some room so that your healer can drink.
A terrifying looking pack. Fortunately, 90% of them will flee when you walk into the room. Hold off your DPS until they go and then focus down the five that remain. Remember to take care of any books thrown.
Pull the Necrotic Spiderlings to the right so we have some room to operate. They'll die quickly but they stack a pretty nasty poison on the tank. 

Next, pull the two enforcers along with the Orbcaster patrol. The Enforcers just deal tank damage and should be faced away from the party. The Orbcaster will charge up a mini spirit bomb which will spin forward killing all in its path. If the Orbcaster is tanked at the top of the bridge then the DPS and healers can dodge the orb by standing at the bottom (it'll go over your head).
Nal'asha doesn't have many mechanics, but she does have a bunch of spiderlings. She'll teleport behind a random player every 30 second or so before casting a large AoE cone attack in the direction she's facing. If you stack up then you can move behind her together when she teleports. This also makes it much easier for the tank to pick up fresh Spiderling spawns. 

On Necrotic week this boss becomes a real terror because Spiderlings attack very fast. Pull the mini-boss down the Thrashbites room to avoid new Spiderling spawns. It's a little slower, but much much safer.
These will all pull together but aside from their cleave they aren't dangerous.

Trash ERT Note

Copy and paste this into the Exorsus Raid Tools Notes section. You can share it with your group.

|cffffff00Cathedral Trash Path|r
Pull the Invader / Destroyed pack.
Pull the three pack to your RIGHT.
Run to the right and wait for the miniboss.
{cross}Dul’Zak{cross}
Pull the patrol with the lone Stalker.
SKIP the two Dreadwings by walking around inside of pillar.
Pull the four-pack patrol.
Pull the five demon pack.
Pull the Mistress pack half way up stairs
SKIP Vilebark Walker patrol by walking over flowerbed.
Clear Agronox’s room.
{skull}|cff8788eeAgronox|r{skull}

SKIP Vilebark Walker patrol by jumping over flowerbed.
Pull imps to the right only.
Clear Thrashbites room – Gazerax last
{skull}|cff8788eeThrashbite|r{skull}

Kill the imp / scavenger pack. Most will flee.
Pull Spiderlings on the right only.
Pull Enforcers and Orbcaster together.
{cross}Nal’asha{cross}
{skull}|cff8788eeDomatrax|r{skull}

Pull the Dreadwings
{skull}|cff8788eeMephistroth|r{skull}

|cffffff00Questionablyepic.com/mythic-plus|r

Bosses

  • Agronox

    Two tree bosses in one expansion. Does the legion have an army of evil trees or something?

     Cathedral: Agronox

    Dungeon Journal+

    Poisonous Spores   AoE   Nature   ✔Avoidance

    Timber Smash   Single Target   Physical  

    Floral Fulmination (Fulminating Lasher)   AoE   Nature   ✔Avoidance   ✔Dodgeable

    Choking Vines (random flower)   Single Target  Nature 

    Succulent Secretion (Succulent Lasher)   AoE   Nature   ✔Dodgeable 

     

    You should know

    • Argonox is a tightly tuned, flower-heavy encounter where all of the mechanics come in waves.
    • Priority is: Run out of Choking Vines > Target Fulminating Lasher > Target Succelent Lasher > Target Boss.
    • Fulminating Lasher’s spawn at the back of the room 20 seconds into the fight, and then a second time 40 seconds later. Five will spawn and they’ll fixate one party member each. These will explode if they reach their target and on high keys this is a one shot. Stun them, slow them, kite them. Do not let them touch you. Stack up to bring them together for more efficient AoE.
    • There are only two waves of Fulminating Lasher’s. After you’ve cleared the two sets you’re done with them for the rest of the fight.
    • At the same time, random flowers will pop up along the side of the room and grip random players in with thorny vines. You can break the vines by moving 20 yards away from the flower (make sure you don’t run into the Fulminating Lasher while doing so). Anyone afflicted will need urgent healing.
    • Overlapping both of these mechanics is a third type of flower, the Succulent Lasher, which spawn in melee range roughly every 40 seconds. These AoE in an 8 yard circle around themselves and drop easy to avoid pools on the ground.
    • [Tank, Healer] Timber Smash isn’t particularly special. It’s just a huge physical hit on the tank every 30 seconds and you’ll need a medium-large cooldown up for each of them. It does have a cast time so you’ll get a very brief second to pop something.
  • Thrashbite the Scornful

    Oakheart’s evil twin, now Smashspites brother. What’s next? Ularogg’s roommate?

     Cathedral: Thrashbite

    Dungeon Journal+

    Pulverizing Cudgel   AoE   Physical   ✔Avoidance   Partially Dodgeable

    Heavy Cudgel   AoE   Physical   ✔Dodgeable

    Scornful Charge   AoE   Physical   ✔Dodgeable

    Stifling Satire (Satirical Book)   AoE   Debuff (Magic, Silence)

    Fettering Fiction (Fictional Book)   AoE   Debuff  (Magic, Slow)

    Beguiling Biography (Biographical Book)   Single Target   Debuff (Mind Control)   Removed at 35% HP

    Arcane Bolt (all three books)   Single Target   Arcane

     

    You should know

    • The types of books that spawn when each bookcase is broken are fixed:
      • Northwest: Fictional Book + Satirical Book
      • Northeast: Fictional Book + Satirical Book
      • Southwest: Biographical Book + Satirical Book
      • Southeast: Fictional Book + Satirical Book
    • You can therefore avoid the Mindcontrolling Biographical book altogether by avoiding the Southwest bookcase.
    • Pulverizing Cudgel and Heavy Cudgel are both pretty basic ‘don’t stand in this obviously bad thing’ mechanics and shouldn’t cause you much issue so long as you don’t tunnel-vision the boss.
    • Scornful Charge will target a player and then five seconds later charge toward them, stopping when he hits a player or bookcase. Immunities are very effective against this ability since on higher keys you’re prone to running out of bookcases otherwise. You’ll also get no book spawns this way which lets you focus more damage on the boss. Use all of your immunities before you break a bookcase by having the player with the immunity step in the way of the charge.
    • (Can abilities be interrupted?)
  • Domatrax

    Don’tbeagenericfellord dontbeagenericfellord… dammit!

     Cathedral: Domatrax

    Dungeon Journal+

    Chaotic Energy   AoE   Fire   ✔Avoidance   ✔Dodgeable (in Aegis)

    Felsoul Cleave   AoE   Fire   ✔Dodgeable

    Frenzy   Soft Enrage 

    Approaching Doom (Fel Portal Guardian)   Summon

    Searing Presence (Searing Overfiend)   AoE   Fire   ✔Avoidance

    Shadow Sweep (Hellblaze Mistress)   AoE   Shadow   ✔Dodgeable

     

    You should know

    • [DPS] Target priority is Fel Portal Guardian > Searing Overfiend (hopefully none) > Hellblaze Mistress > Hellblaze Imp > Boss
    • Chaotic Energy hits every 35 seconds and you’ll need to be within the Aegis of Aggramar to survive it. Try and move into the shield at the last second to preserve its energy and maximise your DPS. The tank can usually take the hit with the help of some cooldowns. You can expect it to hit for around 15 million raw damage on a 20 tyrannical. I’d strongly recommend they do so if they’re tanking any Hellblaze Mistresses since they can easily sweep your entire party out of the shield.
    • Portal Guardians spawn at 90% and 50% health and killing them quickly is an absolute priority. If you don’t get them down within 20 seconds they’ll summon Searing Overfields which can quickly wipe your attempt.
  • Mephistroth

    Where is Mal’Ganis anyway?

     Cathedral: Mephistroth

    Dungeon Journal+

    Phase 1

    Dark Solitude   AoE   Shadow   

    Demonic Upheaval   Ground   Fire   ✔Avoidance   Partially Dodgeable

    Carrion Swarm   AoE   Shadow

    Phase 2

    Creeping Shadows   AoE   Shadow   ✔Avoidance

    Shadow Blast (Shadow of Mephistroth)   AoE   Shadow   ✔Dodgeable

    Fel Blaze (Dreadwing)   AoE   Fire   ✔Dodgeable

     

    You should know

    • Mephistroth is a heal-heavy fight with minimal mechanics for the DPS to contend with.
    • Demonic Upheaval will target two players, and they should move toward opposite sides of the room to make the resulting circles easier to dodge.
    • Players should be spread at least 7 yards apart so that each Dark Solitude missile only hits one person.
    • In phase 2, DPS should coordinate which Shadow of Mephistroth to kill first since keeping their numbers to a minimum is essential.
    • Anyone can control the Aegis of Aggramar. It doesn’t have to be a tank (and if a mobile ranged DPS or healer can take it then the tank can actually add some damage.
    • [Healer] During Phase 2 you’ll be contending with Creeping Shadows with deals an increasing amount of damage throughout the phase. This is a throughput check for you, and your cooldowns are best used here.
    • After your first visit to phase 2, Dreadwings will bombard the platform with Fel Blaze. This is dodgeable and you should do so.