My guild is still steadily progressing. We actually killed Heroic Mythrax a couple of weeks ago. This week we took out Heroic G'huun for our Ahead of the Curve achievement, and then killed Mythic M.O.T.H.E.R for good measure.
Heroic Mythrax
Not a lot to say about this fight, it's very much like Normal Mythrax, just more difficult.
I had an idea for technique for the add phases, but we didn't try it, so I have no idea if it will actually work in practice. Basically, whenever Mythrax starts casting the beam, both tanks pull their add about 10 yards counter-clockwise. The groups, which are usually stacked on the adds, move with them.
The idea here is to pretend a beam is coming towards both groups, and both groups move to avoid it. That way, you don't have to check and see if a beam is coming, which is sometimes hard to tell, and then move. You just always move.
Heroic G'huun
We wiped a lot on this boss last week, learning the different phases. We ended up getting to phase 3 a fair bit, but kept dying to spacing and malignant growth. This week we sorted that out, and got our kill.
It's been a while since we've seen a fight with specialised teams, and orb-running is kind of fun.
I'm not really a fan of the way the second malignant growths start spawning before the first ones have popped. It does make it hard to see the "edges" of the danger zones. But I guess that's part of the challenge.
It was also amusing that we emphasized that healers should heal with their backs to the boss. Kind of like Yogg-Saron, way back in Ulduar. On the next attempt, I followed that plan, then tried to cast Judgement of Light and Light of Dawn, and went, "wait a second...". I never realized that Holy paladins cannot really use that technique anymore.
Mythic M.O.T.H.E.R
We use this cheesy strategy where we send 15 people through the barrier at once, and then pretty much everyone through the second barrier 3 minutes later. We pop a lot of defensives like Spirit Link, Devo Aura, Disc Priest barriers, Darkness, etc, as well as personal defensive cooldowns. As long as you stay in the Spirit Link, you're likely to survive.
It took a few attempts to get that settled, and then a few more to get the hang of the "wall beam, ceiling beam, fire" pattern. One tip is to avoid running diagonally to the safe spot. Run to the gap for the wall beam, then turn 90 degrees, run to the safe spot. Like the sides of a right-angled triangle.
Mythic+ Shrine of Storms +10
On Tuesday after raid, I was asked to heal a Shrine +10. How bad could it be, I naively thought.
Three hours and 179 deaths later, we finally killed the last boss. I hate the Grievous affix. It's especially annoying on the last boss. Grievous stacks on you when your health is below 90%. The healer power buff won't allow you to heal higher than 90%. So that buff must be dispelled immediately and is a non-factor in the fight.
You can cheese the last boss a little. His Sunken City cast is very long, so you can heal up and wait for cooldowns to come back up before interrupting it. Of course, you'll kill the timer doing that, but we had already blown past that.
Most of our deaths were on the second boss, though. The aoe damage from wind slices combined with Grevious were not fun, and it took us a while to figure it out.