Just to consolidate a few things here -
This is not a gear check
You do not need to be in a specific spec
The gateway negates the majority of the encounter
It is well designed because it lets you use your entire toolkit - This is amazing design
It is also good because at my current item level (547) you can literally just blow him up in less than 2 minutes - This is lower item level than normal of next tier so everyone will be able to get this regardless of how 'good' there ability to multi task is
This is one of those extremely rare fights where people might actually think 'wow keybinds would be really handy here' - Now this is SUPER important because world of warcraft atm hands everything to everyone and very rarely asks you to think for yourself.
If you are having trouble with this quest and genuinely cant get it with this tier's gear then come back next tier when your bigger and better, the reward is still waiting for you, and if you cant get it next tier come back next expansion when you will probably 1 shot the clown, the thing is with that when you do its gna be the most satisfying 10 seconds of your life (virgin / not virgin depending) because you will have put so much effort into killing it and you cant buy that feeling.
To everyone who is still struggling with it i wish you all the best of luck but dont give up and dont stress yourself on it either.