Guardian of the Menagerie, the Curator hits for around 3000-3500 on tanks with normal attacks and has 690,000 health.

Astral Flares

Every ten seconds the Curator will summon an Astral Flare.  Each flare has 15,000 health and will target and approach a random raid member.  The flares have a chaining arcane lightning attack that will hit multiple players should they be too close.

The method for avoiding such things is to have each raid member stay at least around 15 yards away from everyone else to prevent any chaining damage, should it chain it hits for around 700-800 damage and is used every second.

A total of ten Astral Flares can be summoned in-between Evocations.

Hateful Bolt

Once every ten seconds or so the Curator will fire a Hateful Bolt at the highest HP target who is not the main tank/target.  The bolt deals around 4000 arcane damage.  To prevent this from hitting anyone unnecessary you can have an off-tank with the most hit-points out of the raid, making him the guaranteed Hateful Bolt shield, just remember to heal him or else he won’t be targeted due to his lower HP.

Evocation

After the Curator summons the tenth Astral Flare and uses the last of his mana, he will enter an Evocation phase for about twenty seconds.  This replenishes his entire store of mana but also makes him vulnerable to 250% damage debuff, this is when you pop all the cooldowns and burn him down as much as possible.

Enrage

At 15% health the Curator will cease spawning Astral Flares and increase his melee damage and attack speed instead, also by result increasing his Hateful Bolts.  This is when focused healing really needs to be utilized to keep the tank up, that and the off-tank/hateful bolt soakers HP.

The Pull

The Curator, unlike most other bosses in Karazhan so far, has an immense aggro range of about 45 yards or more, meaning that to get your positioning and set-up correctly inside his room you’ll have to wait until he walks all the way around the corner at the end of the room.

Once the Curator paths away you can move in set up positions as required, remember, ranged DPS should all be spaced out at least 15 yards from one-another in something like a large half-circle around the Curator’s tanking spot.

After everyone has reached their designated places you can have the tank pull the Curator towards the center of the room, keeping him directly in place to prevent any required repositioning mid-fight to compensate for range and such.

The Fight

Once the boss has been engaged you should be watching for the first Astral Flare, as soon as it appears you’ll want all your ranged DPS to be focusing on burning them down as much as possible.  Melee DPS however will want to be sticking to the Curator to avoid getting hit with chaining Arcane Lightning and therefore reducing the healer’s requirements.

After this first spawn you’ll need to keep up the DPS and continue to focus fire the Astral Flares down as fast as they get summoned, otherwise you risk stacking Arcane Lightning from multiple Flares on either healers or even your DPS, dropping players or just mana pools at the very least.

Once the final flare comes out you’ll be left with deciding to either DPS the flare and then drop onto the Curator himself or to simply go after the Curator and deal with the flare after your 20 seconds of dominance end. 

This decision lies solely on your healing and DPS capacities, if you can drop the flare easily enough, you might as well, if you also need the mana for later healing do this as well, otherwise if you feel you can go for it, beat up on the boss the whole time.

These Phases repeat, burning down flares, burning down the Curator during evocation, this is the same until the Curator reaches 15% health and he’ll stop the summoning of Flares.  At this point DPS simply needs to focus fire the Curator as fast as possible, do this before your healers run out of mana and before the boss enrages and wipes your raid.