A couple of groups in my guild took a crack at Malygos/10 yesterday. She's hard! Fun fight, a good challenge, nice to see a boss we can't kill the first time we see her. Every phase has its challenge: healing and spark placement in phase 1, disc flying in phase 2. And dragon control in phase 3.
Phase 3 of Malygos is one of those obnoxious fights where you possess another creature and use its abilities; like Teron Gorefiend constructs or the last boss in Occulus. The abilities are totally different to what you're used to and it's hard to learn it on the fly in the middle of a raid with an enrage timer ticking. Fortunately, Blizzard thoughtfully built a Malygos simulator right in the game for you to practice on. Even better it's a daily quest that gives you Wyrmrest reputation! Here's how to do it:
At level 80 go to Coldarra, in Borean Tundra, and speak to Librarian Serrah in the shield at 33.5, 34.4. She has a quest for you to speak with Corastrasza. No prerequisites, but you do have to do this trivial quest.
Go to Corastrasza. She's up high on a platform a bit to the northwest at 29.5, 24.8. Turn in the quest and accept the new quest Ace's High. Once on the quest, talk to her to mount a dragon.
The dragon abilities in this quest are identical to the Malygos raid dragon you ride. It's a weird mix of rogue-like energy and combo points, stacking DoTs like a Warlock, stacking HoTs like a Druid, and a damage shield that saves your life against the giant Arcane Surge. I've done the quest twice now and have a pretty good feel for how the DoTs stack, but still need to get more comfortable with managing energy and making sure I'm always ready to put up my shield.
Malygos dragons causes all sorts of UI issues with addons. When you're mounted on the drake you should see your own frame turn into a vehicle / pet. That vehicle has combo points; either against itself when healing or against the enemy when DPSing. It also has an energy bar. XPerl was giving us a lot of trouble last night but claims to be fixed now. XPerl 3.0.2 which I just installed does work on the Aces High daily. The Malygos Helper addon also works on the Aces High daily, although it's not very interesting when you're alone.