I was in the 360's and doing like 8-10k looking back at old video's i recorded. The biggest for me was just finding what worked for me and how I play. I want to have fun and play like how I like to play, so I just found what worked. Survivability is the name of the game on some boss fights. You can only out dps things so much, then I find I have to stagger my heals well, use turtle shell at smart times, survival of the fittest from the tenacity pet helps, moving out the poop helps. LOL
I imagine if I had the other windows visable on another monitor it would be easy to just switch to the toon taking the beating and move him easily, but I'm on 1 monitor and all my windows are just stacked, so lots of Alt Tabbing if needed.
I would just keep trying till you figure out what works on that guy. Or just run others and gear up a bit more, it comes pretty easy with world quests, warfront stuff and mythic 0. even run heroic just to get a feel for the fight if need be, i did that a lot when I first started. Lots of normal and heroic, then mythic and mythic +.
