Cathedral of the Eternal Night Guide:
   The Trash at the beginning are named the Felguard Destroyers, they have a spell called: Shadow Orb. This reduces the damage taken while mobs are inside this circle by 75%, so remember to kite the adds out of the orb, and interrupt this ability.
The Soul-menders have a demonic mending cast, this simply heals friendly targets, so interrupt this cast as well. The Felbringers will drop a Yellow globes on the ground, and while you stand inside of them, you gain a 50% haste buff, but take significant damage, so kite the adds outside of the globe, and have your DPS stand in this orb, assuming the healer can keep them alive.
On the left side, of the entrance, there is a mini-boss surrounded by trash mobs, listed above. This mini-boss has a single ability called: Shadow Wave. This ability sends a cone of shadow energy towards a random player, dealing immense amounts of damage (this can instantly kill players) whilst leaving a pool of shadow energy on the ground. So pulling this boss, among the trash can make a deadly encounter. You can mitigate this, by CCing the adds or simply setting a kill order, and interrupting key abilities.
The bats flying around the inner ring of the room, can be aggro'd and pulled. They do have some nasty abilities, such as Shadow Swipe, which will knock back your tank, and this can lead to extra trash being pulled if you are not cautious.
The Shadow stalkers will patrol the outer ring, once aggro'd, they will teleport to a random player, and cast Devour Magic, which will silence players that have stood in this, so move out of this ability.
The trash leading to the First boss, will fixate on random players, and once they have reached their target, they will explode and deal immense amounts of damage, so be aware!
The "Wicked Walkers" deal AoE damage and knock back players, so out-heal this and be aware of surrounding trash packs.
Interrupt the Succubus' channeled MC ability, and interrupt the Botanists'  Blistering Rain, which does ticking AoE damage to your entire group, on top of a Rejuvenation, which heals nearby mobs. Interrupt both of these abilities.
FIRST BOSS: AGGRONOX (One Phase, One major ability, among spawning adds)
	The boss will spawn Flower adds that will fixate random players, once they have reached their target and only their target, they will explode and dealing immense damage to the fixated player, so kite these adds and nuke them down ASAP.
	Tanks: You will need to use your active mitigation on the Timber Smash ability. This hurts like a truck.
The boss will also apply a poison De-buff, that will kill players after a certain amount of stacks.
		In short: Avoid add pools and fixates > Kill adds > Kill Boss
SECOND MINI-BOSS: GAZERAX
	He will cast Blinding Glare, this will do a massive Area of Effect ability to your entire party, just face away from the mob once he begins casting this spell to avoid the majority of the damage.
SECOND BOSS: Thrashbite the Scornful (One Phase; Three abilities)
	Melee and Tanks: Watch for Pulverizing Cudgel, this ability will deal damage to the whole group, but WILL instantly kill players that stand within 15 yards of him.
	Ranged and Healers: Stand in the inner ring of the room, because once the boss casts: Heave Cudgel, he will throw his weapon outside and cause a Whirlwind, this will instantly kill players who stand in this, so be aware!
	Scornful gaze, you will need to move behind a bookcase to avoid being one shot, but essentially, once the boss slams into a bookcase, he will be stunned for a few seconds, so focus your damage on the boss once this occurs.

	After this boss, players will climb a staircase coated in Spider-webs, adds will then appear which will deal stacking and ticking damage to your tanks and will leave poison patches once they have died, so limit AoE, kite the adds, and kill them, before the tank is killed.
THIRD MINI-BOSS: NARLASHA
	She will vanish and cast a conal ability that will instantly kill players caught in it, so move out of that ASAP
She will also leave patches of Spider webs on the ground, which will slow you, reduce your haste and damge you, so be smart. Move out of these.
THIRD BOSS: DOMATRAXS (One Phase)
	The Aegis of Agrammar, will be in the middle of the room, only stand in this during spikes of high damage, as this will reduce the damage you take by 90%, but will reduce the amount of healing and damage by 75%. this aegis also has an energy meter, so once it is depleted, you can no longer gain it's effects. <CHAOTIC ENERGY>
At 90%, the boss will open two portals and two portal guardians, these adds will hold open portals which summon imps, so burn these guardians down ASAP
At 50% this phase will repeat, but on Mythic, instead of Imps, the portal guardians will summon Burning Mistresses, which will deal immense Area of Effect damage to ranged players, so tanks, pick these adds up, nuke the guardians THEN the Mistresses THEN the boss.
At low Health, the boss will go into a Frenzy, which will increase his attack speed, so healers try to save CD's for this part of the phase and tanks use active mitigation.
FOURTH BOSS: MEPISTROPH  (Two Phases; Three abilities - P1; One ability - P2)
	Carrion swarm: Tanks face the boss away from your party, this will deal massive damage to anyone in the cone and leave a patch on the ground.
	Dark Solitude, this will deal damage to your party, and DOT random players, Spread apart so, you don't take extra damage
	Demonic upheaval, this will spawn a Fel Spire after a few seconds, so pop them on the outside of the room, and move back in.
PHASE 2: Tanks, use the Aegis to soak the Shadow orbs heading towards Illidan and let him finish his cast.
		Phase one repeats after this, burn the boss.

GOOD LUCK FOLKS, HAVE FUN, AND I'LL SEE YOU NEXT TIME! - Kami