3 phase encounter that will test your ability to deal with multiple mechanics coming from multiple sources.
During the fight, you will only be able to attack one of the Sisters at a time, while the others will be ghostly and still casting their abilities that the raid will need to be attention to. When one sister is out, they gain new abilities and while they are ghostly maintain the same ones throughout the entire encounter.
The floor is made to look like phases of the moon and throughout the encounter it will change phases.
**While standing on the light side of the room, you gain a stacking debuff of Lunar Suffusion, which increases ARCANE damage done to you by 3% each stack.
**While standing on the dark side of the room, you gain a stacking debuff of Umbral Suffusion, which increases SHADOW damage done to you by 3% each stack.
Switching from one color to the other will deal both types of damage to you and clear all your stacks of one debuff and put another debuff on you, refreshing your stacks, essentially. This is called Astral Purge. (You gain Astral Vulnerability by Purging yourself which will increase the damage you take from Purge by an additional 50% to prevent you from spam clearing your stacks.)
When the floor is entirely dark or light, whichever boss you are fighting will empower with a different ability.

PHASE ONE: The Huntress

Tanks will need to stand near each other to share the damage of Moon Glaive.
Moon Glaive - Attack that will first hit the tank and then two other targets for heavy physical damage. Tank will want to use an active mitigation for this. The initial target will get a debuff that will reduce their healing and absorption taken by 75% for 30 seconds. This debuff can be removed early with a taunt swap and triggering Astal Purge.
(If the room is either all dark or all light and no Purge can be triggered, the tank will just want to taunt swap and wait out the 30 second debuff or the room to change, whichever happens first).

She will randomly mark a player with Twilight Glaive and point an arrow towards them. After a few moments she will fly towards that player and then go back to her original location. This will cause her to deal heavy Shadow Damage to that target. If you have high stacks of Umbral Suffusion, you will want to pop a personal cooldown or have something like Life Cocoon/Barkskin to mitigate.
Also you could be fairly close to the light and dark line so that if you are targeted you can quickly clear your shadow stacks before this ability hits you.

In this phase you will be fighting the Huntress, worrying about her Twilight Glaive on the ranged, and her Moon Glaive on the tanks. Whilst the Priestess and Captain are throwing out their Lunar Strike and Shadow Shot.

The Captain will deal moderate amounts of Shadow damage to players in this phase similar to Lunar Strike, which is called Shadow Shot. Players will need to be spot healed/use personals whenever possible and remove the debuff with triggering Astral Purge.
Again, healers should note those with Umbral Suffusion stacks since they will be taking more damage from these abilities.
She will cast Twilight Volley which will rain down arrows on a random player, leaving behind a zone which slows you and deals shadow damage to all those inside. This will only target ranged players, so ranged should avoid being in melee or on the tanks.
When the font is fully dark, the captain will cast Incorporeal Shot, which will randomly mark a player and shine a beam towards them. After 8 seconds, that target will take lethal shadow damage that will be divided by everyone standing in the beam. If players have high stacks of Umbral Suffusion, raid wide cooldowns should be used here. (Players will want to watch the font and if you have high shadow stacks move to clear them before the font becomes fully dark to prevent higher stacks).

The Priestess will randomly target players with Lunar Strike and Moon Burn.
Moon Burn is a debuff that will do a moderate amount of Arcane Damage to the player every 2 seconds for 30 seconds. This ability can be dispelled by triggering Astral Purge. Players will need to actively try to Purge this when possible. Otherwise, use personals/spot heal and wait out the debuff.
Healers should note those with Lunar Suffusion stacks since they will be taking more damage from these abilities.
Lunar Strike is just a spot damage ability that deals arcane damage to players. (cannot be avoided, use spot heals)

When the Huntress is at 70%, and you will fight Captain Yathe Moonstrike and primarily dealing with her.

PHASE TWO: The Captain
During this phase, the Huntress will still be throwing out her Twilight Glaive, but this time she will be teleporting around the room, so you will have to constantly keep an eye on her positioning to move out of the way of the Glaive. The huntress also gains a Spectral Glaive ability.
Spectral Glaive will hit a random player and then up to 3 nearby targets dealing low shadowspell damage (Spreading out will reduce the amount of times it will bounce.

The Captain no longer does Shadow Shot, but gains an ability called Rapid Shot, which deals Shadow damage every .5 seconds for 5 seconds. This player will need significant spot healing.
During this phase, She will have a Moontalon by her side, which should be switched to immediately. The Moontalon will frequently cast Deadly screech, which will deal significant Shadow Damage to all players around her. The damage increases by 25% each time it is cast.

The Priestess will maintain her Moon Burn and Lunar Strike abilities. During this phase, when the Font of Elune empowers, she will put a damage absorb shield on the captain (30 million) as well as smaller ones on each player (1 million) and after 12 seconds, it will explode and deal damage equal to the amounts remaining. Players will need to quickly damage the Captain and use raid cooldowns to heal everyone through the absorb shield. The range of the Captains absorb shield explosion is 70 yards and each player's individual explosion is 8 yards, so separate during this in case the shield isn’t absorbed.

At 40% Health the Captain will turn incorporeal and the Priestess will come out to play.

PHASE THREE: PRIESTESS LUNASPYRE
The Priestess will maintain her Moon Burn, with players triggering Astral Purge to remove the debuff. However, instead of Lunar Strike, she now casts Lunar Fire, which applies a debuff to the tanks dealing arcane damage every 2 seconds for 30 seconds, so tanks will need to taunt off for this.
She gains a new ability called Lunar Beacon.
This is a 6 second debuff that will deal moderate damage to play player for the duration. Once it expires that location is bombarded with Lunar Barrage for 2 seconds after.This will deal high damage and silence those in the zone, so it’s important for those who get this debuff to move away from the group. These players will need spot healed, especially if they have high Lunar Suffusion.

The Huntress will maintain her same Twilight Glaive and Spectral Glaive as before.When the Font is empowered, she will throw a Glaive Storm and then shatter into multiple glaives that will form a line across the encounter area. They will move in the opposite direction towards the edges of the room. Any players hit by the glaives will take heavy arcane damage. Players should avoid the centre of the room.