Curator

Trash Mobs:
There is a back entrance for reaching Curator that can be reached outside Karazhan across the river, to the north of the main entranceway in Deadwind Pass. It is found climbing the tower there and across a small overpass bridge. To reach Curator the raid enters the side entrance and will be bearing to the left. There are mobs right around the entranceway so the raid should be careful to avoid easy aggro as they prepare.

There will be a stairway to the left that shall be climbed in order to reach Curator. If the doors around the stairs are taken you will see the area that belongs to the summonable creature; Nightbane. This can only be done once someone has completed the series of quests related to him through Karazhan.

There are several twists and turns that will lead to Curator but it would be difficult to get off track from this point on beyond the stairway as you progress towards Curator. There will be single ghost elite pulls along the way until the point where the raid reaches the sentinel creatures. Double tanking will be necessary on this phase and attention to who gets debuffs so as not to hinder the raid(explained below). After the sentinels have been defeated the raid will move into a circular room with a pillar directly in the center. This area will be where all the remaining combat will be done before Curator. Curator is pathing/patrolling a route in the next room next to the groups of mobs that will be brought out each time that he paths away from the raid into this circular room. After all the trash mobs have been defeated the raid moves in to the hallway against the far wall so as not to aggro and prepares for Curator.

Ghosts
Difficulty: 1 elite, significant damage.
Special Abilities: melee.
Strategies: These mobs can be slowed and kited around, so even if your tank drops you can still finish off this mob if your hunter/frost mage is careful. These are usually straight forward tanking and dps battles that go relatively quick.

Sentinels
Difficulty: 1-2 elites, moderate damage.
Special Abilities: melee, arcane explosion debuff (placed on raid members who are the source of the explosions, arcane missiles.
Strategies: When there are two of these to contend with, split the tanks up and have a healer assigned to a particular tank that they are responsible for. Throughout the fight, they will randomly place an arcane marker on raid members. This raid member will start casting arcane explosion on himself and those around him. As soon as you have this debuff you should remove yourself from the raids location so that you do not inflict damage to everyone around you; the damage gradually gets worse as it wears off.

Arcane Packs
Difficulty: 1 elite, 5-6 non-elites, moderate damage.
Special Abilities: mana drain, blink(deaggro), melee.
Strategies: All the arcane packs shall be fought in the circular room before Curator as described above. It is best to take down the elite mob first while fearing all the non-elites in the group with warlock/priest/warrior fears. Once the elite mob had been slain, he will restore mana to the raid members that are near his body for the next 10-15 seconds or so. This will help restore lost mana thus far from drains and the fight on the elite. The non-elite mobs should be destroyed quickly thereafter.

Curator::

Curator goes through two primary phases throughout the battle. Curator starts the battle with full mana but spends 10% of his mana every 10 seconds creating an arcane creature to assault the raid (Curator is immune to mana draining in all respects). The tank should be on Curator while all members in the raid focus on the non-elites that are spawned at every 10 second interval.

The formation of the raid is important for this fight and restricting yourselves to two primary rules. One healer should be responsible for keeping the tank up and another for the members of the rest of the raid that will deal with the spawns. The first rule relating to the formation is that everyone must spread out away from one another so that damage will be reduced to a single area. The spawns use arcane explosion as they move around to their targets and this damage can easily get out of hand if it is hitting more than one individual.

The second rule to this may seem simple but usually people have a hard time grasping; don't move. It is some sort of instinct for people to simply backup or blink away from a mob that has aggro on them in an attempt to keep their distance. "DO NOT MOVE". Moving will only hinder the raid since you are putting other raid members near you in danger. Just think of it as you becoming the temporary offtank for this spawn. Often the mob will not change aggro despite what is being thrown at it. Become a hunter/mage tank for the next 10 seconds and just take the hits (swing your sword/polearm hunters).

No dps should ever be on the Curator. It is imperitive that while adds are spawning the adds are the ones to go down. Damage to Curator happens when phase 2 approaches. Curator will run out of mana after he spawns the 10th arcane creature. At this point in time, he will go into an evocation mode to regain his mana and arcane creatures will stop spawning. While he is evocating Curator will receive 200% damage from anything that strikes him.

It is tempting to immediately start dpsing him when you see that he has begun his evocation. "DO NOT" do this right away. He will spawn his last non-elite when he evocates, and this is the mob that must go down before any dps goes on Curator. This will be the failure of your raid, because as soon as the spawns get out of control chaos pursues.

When the last spawn has been killed everyone must unload everything that they have on Curator since he will be taking double damage for the remainder of the evocation...pom pyro's, call/send hunter pets, throw up dots and instant splash damage, pop trinkets, etc. This is the perfect time for priests to use their shadow fiends since not only will it do more damage, but it will restore double the mana back to you than you are normally seeing occur. Priests should not use a pot in the first phase and should rely on the fact that their shadow fiend will restore all their mana back in this first phase for them. Dust off your wands and throw them as well, they might be hitting for 600-800 a hit.

It is customary to go through a couple phases like this one before Curator gets to around 20 percent health. At 20 percent health Curator will enrage and stop spawning arcane creatures. At this point he will hit harder but the battle has switched gears now. This is a tank and dps section of the fight at this point and usually means your raid has succeeded in defeating Curator unless something terribly wrong happens.

How to video for reference:
Curator: How to Fight.