Few can resist the whispers of the Old Gods, but those who do find themselves at the "mercy" of Dark Inquisitor Xanesh. A cruel and sadistic torturer, Xanesh prides herself on slowly carving the sanity away from those in her charge until all that remains is unwavering devotion to N'Zoth.
This is a single phase encounter where the core mechanics of the fight are handled by set members of the raid. However, how you position the boss is vital for this mechanic.
During this encounter you will observe Azshara who is trapped in the centre of the room and the boss Dark Inquisitor Xanesh.
Anguish - This is low ticking shadow damage which deals damage for the entire encounter, it is unavoidable.
Torment - This is cast on Azshara by Xanesh which will then make Azshara erupt with Void energy.
There will be 3 pulses of void energy in total, for this the room will be divided into 8 segments.
Alternate segments of the room will be filled with Void for pulses 1 and 2, and for pulse 3 only 2 segments (which are directly opposite each other) will be free of the void energy. You can see this in action below.
The first two will be side step-able, the third you will want to already be moving for just in case the worst case scenario happens and you need to move across two segments.
Abyssal Strike - This is the tank swap mechanic of the encounter. It will leave a debuff which lasts 1 minute, however this ability is only cast every ~45 seconds, so you can swap every cast. This ability will also knock you back, so ensure you do not fall off the side of the room, or into Queen Azshara.
Touch of Pain - The melee ability on this boss was renamed to this, this may change when the boss is Live.
Soul Flay - This will target several non-tank players and they will see a very bright orange spawn animation. After 10 seconds they will take Shadow damage based on their distance away from it.
Void Ritual - This is the main mechanic of the fight. 3 eyes will spawn on the floor, one directly behind the boss and one either side.
The players stood inside of this will become 
Voidwoken which will reduce the damage they deal by 99% but allow them to interact with the 
Void Orbs.
The players that are Voidwoken will need to knock the Void Orb from its spawn position to the Portal on the other side of the room.
If any players who are not Voidwoken touch the Void Orb they will be knocked back and take damage from 
Revile.
The Void Orb will be knocked based on the direction your character is facing your movement/trajectory does not matter.
If the Void Orb hits the side of the room, or the Void around Azshara, it will trigger a 
Dark Collapse which will deal large damage to the raid and buff the boss with Dark Ascension and 
Fanaticism.
Once the mechanic has finished the Voidwoken players will receive a 
Void-Touched debuff, which will mean they cannot become Voidwoken again for 3 minutes and will take ticking Shadow damage for the duration of the debuff.
[Heroic] 
Imminent Doom - When a Voidwoken player interacts with the Void Orb they will have a stack of this applied to them for 12 seconds. If they reach 5 stacks of this, they will trigger 
Doom and die.
[Heroic] 
Summon Ritual Obelisk - Obelisks now spawn around the room acting as additional pieces to avoid interacting with during the Void Orb mechanic as touching any of these is the same as Azshara or the edge of the room and will trigger Dark Collapse. There are 3 patterns that I observed for how these spawn:
The changes to this fight are all centred around the Void Orb mechanics.
Imminent Doom - The amount of debuffs you can get before this triggers Doom is now 3 (down from 5).
Void-Touched - This debuff is now permanent, this means you will require more people to execute the mechanic.
Dark Collapse - This now deals Lethal damage, therefore if any Voidwoken team fail, it's a wipe.
Awakened Terror - Each time the Void Orb is interacted with an Awakened Terror add will spawn. This add will cast 
Terror Wave repeatedly. This cast can be interrupted but should be killed as soon as possible as you will have multiple spawn.
Ideally you want to complete the Void Orb run with as few interactions as possible to maximise boss damage.
Summon Ritual Obelisk - The amount of Obelisks spawned is increased significantly and has set patterns to follow. Unfortunately not many groups on testing got very far, so this section of the guide will be updated once this has gone live. Linked is an example of the first Obelisk pattern on Mythic.
Swap on each stack of Abyssal Strike (Mythic: Swap on 2 Stacks)
Ensure the boss is positioned in a way that the Void Ritual is safe to stand in
If you are tanking near the edge of the room, place 
Transcendence down so you can teleport back up if you get knocked off
Infernal Strike can be useful to avoid the last hit of Torment
Fiery Brand can be used to mitigate the damage from Abyssal Strike
[Mythic] 
Sigil of Silence can be useful to interrupt the Awakened Terror you are not attacking when multiple are up
You can block Touch of Pain
Blessed Hammer works to reduce the damage from Touch of Pain
Blessing of Spellwarding can be used to negate the damage from Abyssal Strike but will not negate the stack
[Mythic] 
Avenger's Shield is very useful for keeping the Awakened Terror's interrupted
Spell Reflection can be used to mitigate the damage from Abyssal Strike
Heroic Leap can be useful to avoid the last hit of Torment
You can deflect Touch of Pain with Spell Reflection
Stampeding Roar can be very useful to help people move from Torment
Anti-Magic Shell can be used to mitigate/negate the damage from Abyssal Strike but will not negate the stack
Death's Advance can be used to negate the knockback from Abyssal Strike