This boss will probably be the hardest we've fought in the tier so far. Most likely exceeding Imonar in difficulty, this fight reminds me very much of previous fights such as Star Augur Etraeus. If we accomplish the following two goals this fight will be ours.
1. Learn how to handle each Wombo Combo one by one. 2. Learn how to win the war of attrition ENOUGH that will allow us to kill it. This fight will not come out and wipe us in one fell swoop. It will pick players off one by one over the course of the fight. That will slowly put us behind in terms of damage or healing as the fight goes on.
So, let's get into it. What could possibly make this boss so hard?
What's Different on Mythic? This fight honestly doesn't have too many "new" mechanics on Mythic. We will see a new member of the Coven during the middle portion of the fight with only two simple abilities. However, it's how the Heroic mechanics have been rearranged that makes Mythic hard.
Boss Setups Throughout this fight, we will see either one of two sets of Coven members; Noura/Asara (Fire/Shadow) during the first and last 3 minutes of the encounter and Diima/Thu'raya (Frost/Fel) in the middle 3 minutes. A recap of their abilities can be seen below along with a brief description of Thu'raya's two abilities (which are quite simple), but should be handled with care.
It should be noted when Noura/Asara are up, Melisan as DPS will be tanking Asara while Viperx and Astaroth will swapping off Noura at two stacks.
Handling Wombo Combos Throughout the Fight Like previous fights such as Etraeus, this fight is filled with nasty wombo combos that will slowly pick off raiders asleep at the wheel. 1-shot mechanics are all over the place in this fight. It's important that you pay attention to these 1-shot mechanics (such as Whirling Blade, Touch of the Cosmos, Shadow Blades, etc.) while other big things are happening (ie. Adds, Safety Zones). If you don't, you will most likely die.
Below I have gone through the fight and labeled every "major" event with time stamps (there's a plethora of smaller ones as well). It's important everyone knows what to do in every one of these situations. It should also be noted here that yes, the spawn order for the titan adds is preset on Mythic.
Norgannon Add CC's One huge part of the Mythic version of this encounter is basically "removing" Norgannon adds from the encounter via hard CC'ing every single one of them. Easily the strongest CC's for these are AoE death grip from Blood DKs and Mass Entanglement from Druids. Below you can find our initial CC assignment setup for the encounter along with what side of the room each person should hang around to help keep the raid spread out. Please keep in mind this can change once progression starts and we find certain things do/don't work.
Take note that we still have some CC's left over after all these hard CC's are assigned (Bellasaer's Blind, Aily's Holy Word, Junkr's Frost Nova, etc.). These can be used as backup hard CC's if certain players die during the fight (which will most likely happen).
Guide Videos The following three videos are all pretty decent videos to watch to get different perspectives on the fight. I recommend watching at least one of them (Jak's healing video is ~8min, Kelade's Fury Warrior one is ~8min, and Method's guide is ~14min).
Method's Guide to Mythic Coven of Shivarra (Very Good Guide, I recommend this one most.)