I was bored and decided to give this a shot since I had a raid id saved at Yogg from trying to solo him in 5.3. Not to bad as I ended up 2 shotting it. I did this at a 546 ilvl. I was in t15 4pc, but if you can get t16 4 pc, I would imagine this fight would be much easier. Glyphs used were Templar's Verdict, Divine Protection and Divine Storm. Eternal Flame was the only talent that wasn't standard that I picked up. Sanity shouldn't be an issue any more, Psychosis no longer reduces sanity, which I found out in the first attempt. Malady is now cast while soloing, but has little effect besides losing control for a few seconds. So in phase 3 you won't have to play to conservative and limit the time looking at Yogg. Good luck in farming for your Mimiron's head.