For this fight you will need a macro:
/target Astral FlareYou will be using this the entire fight. What will happen is your Tank will attack Curator. Curator will spawn 10 Astral Flares and then go into Evocation. While he is in Evocation he will be inactive for 20 seconds and will take 200% more damage. You have to take down all the Flares ASAP so you can get into the action of Evocation.
At the beginning of the fight put your pet on Curator and start spamming your target macro. If there is nothing to shoot you will automatically attack Curator. Keep spamming until you get a Flare and then DPS the hell outta it. If it comes after you you can either FD or just melee it down. I usually have my 1H weps on for this fight. Seems like in the raids I have been in the Flares ping pong between Grumble and I so even if you are meleeing it gives other hunters a chance to range it.
Once all the flares are down turn to curator and pop all cooldowns. Get as much damage on him as possible. Your tank has been on it this whole time so there should be no way you could pull argo. Wash, rinse, repeat. Keep doing the cycle until he is down. Once he has been fighting for 10 minutes he will enrage and kill the group but usually he will be dead anywhere between 3-7 minutes depending on your raid strength.