Put out 3 Fire Elementals, blow all cooldowns DO NOT HEAL paladin and just dps this shit outta him. Pop all cooldowns, whatever. With conquest gear he should drop in about 18secs. Make sure you have everything setup right before you engage him, those precious seconds when he starts casting is not the time to stop and figure out what you need to cast. I did all that plus bloodlust and he didnt even finish the second insanity cast, but once he died all your mirror images will still be there. The good news is you will get the achievement even though you will most likely get slaughtered by two groups of mirror images. You can still loot him after hes dead and you zone back in.