Also, just for kicks and to keep the record, this was the writeup I did originally for our strat, which uses a more traditional setup (and what I would argue is the "intended" method for this fight), but as you can see it is very complicated and requires near-constant swapping from the entire raid.
WARNING: AGAIN, THIS IS NOT OUR CURRENT STRATEGY, DO NOT MEMORIZE (LULZ)
It's time to revive the discussion for... Stay Chill (OH BOY!):
The key to this achievement is a proper strategy and personal execution -- everyone must know what they are doing and when, and not hesitate to take the next step in the sequence.
Here is our team setup and distribution:
Nezir Full-Time
Vikrum
Team A - Nezir / Anshal
Ansum
Bauser
Guide
Harkle
Kilwenn
Kulldon
Team A - Nezir / Rohash
Boheem (or Harkle)
Team B - Rohash / Nezir
Kainhighwind
Team B - Anshal / Nezir
Duux
Takaoni
Yes there are 11 people listed, such that Team A - Nezir / Anshal will have 1 fewer persons depending on the raid comp at the time. Team A - Nezir / Rohash is ideally Boheem, but if he's not present it will be Harkle.
You may or may not remember this table, which outlines the overall timings of stack counts:
To review, the above table illustrates the moment a particular team will be on Nezir and getting a stack application. Thus if a number is not listed for a particular row for your team, it means you are on your appropriate secondary platform (Rohash or Anshal, respectively) for that stack application.
To make it more specific to each team, the following tables break it down by each of the four team types.
Team A - Nezir / Anshal
Team A - Nezir / Rohash
Team B - Anshal / Nezir
Team B - Rohash / Nezir
Throughout the fight, we'll of course be calling the stack applications, so teams know when to swap. The tables may seem more complicated than the reality, the general rule is, once the rotation begins after the first Ultimate, teams simply swap every new stack application.
Therefore, as an example, we can see that for me, as a member of Team A - Nezir / Anshal, I'll start out on the Nezir platform just before the first Ultimate, so I get that first application right before. After the next application after the Ultimate, I'll start my rotation process, moving over to Anshal once Cast #2 happens (also happens to be Stack #2 for me). Once Cast #3 hits, I'll move from Anshal back to Nezir, so I can be there for Cast #4 (Stack #3 for me), and this repeats.
Overall Strategy
We split into normal groups with 2 DPS on Rohash and 3 DPS on Anshal as usual. We have about 2:45-3:00 minutes to get Rohash and Anshal to ~100k HP (obviously Anshal heals slightly, but 100k is the goal), so teams will need to be careful of DoTs when percentages are getting low.
The timing will mean we go through one full phase+Ultimate, then nearly a second full-phase, before we start our actual rotation just before Ultimate #2. Since we want Vikrum plus Team A on Nezir just before Ultimate #2 when we start the rotation, Vikrum will start the fight on Nezir with Taka on Anshal. Here is the specific locations for the pre-achievement rotation portion of the fight:
Start to Ult #1
Anshal: Kainhighwind, Takaoni, Ansum, Bauser, Guide, Kilwenn
Nezir: Vikrum, Kulldon
Rohash: Duux, Boheem, Harkle
Ult #1 to 70 Energy
Anshal: Kulldon, Vikrum, Ansum, Bauser, Guide, Kilwenn
Nezir: Kainhighwind, Takaoni
Rohash: Duux, Boheem, Harkle
@70 Energy/Rotation Start
Anshal: Kainhighwind, Takaoni
Nezir: Kulldon, Vikrum, Ansum, Bauser, Guide, Kilwenn
Rohash: Duux
This will put everyone in the right positions as we start the stack rotation and should give us the DPS we need to burn Anshal/Rohash quickly before Ultimate #2.
At 70 energy before Ultimate #2, we make the final transition to prepare for our rotation, bringing Team A onto Nezir for that final Wind Chill stack before Ultimate #2. From there, we follow the rotation outlines above and it should be smooth sailing.
As soon as Team is is about to hit Stack #5, we'll Bloodlust for Team A and they'll prepare to kill Anshal and Rohash as they land after that Stack #5. From this point on, both Team A and Team B remain on Nezir the rest of the fight, and we should reach our 7th stack on Team B with ~10 seconds remaining on Gather Strength.
Player-Specific Tips
Tanks:
Vikrum will be our full-time Nezir tank once the process begins, which means his debuff stack will get quite high. Also to help healers, if possible we need Vikrum to bubble off his Wind Chill stack when it hits 4 stacks the first time after the rotation starts. This will give him enough time to re-up to 7 stacks before the rest of the raid is hitting 7 and we finish off the fight.
If bubble doesn't work, once Rohash and Anshal are dead and thus Team B is on Nezir full-time, we'll want Taka to grab Nezir to lower breath damage, as he will only have 4-5 stacks of the debuff compared to Vikrum's 9-10 at the time.
Nezir positioning will be very important during the rotation, so that healers landing on Nezir's platform can be in heal range of the tank. Splitting the difference along the closest edge so the cone attack can be faced away seems best, like so:
Healers:
I have the teams setup with me as the Team A healer so I can actually see what is going on, specifically between Nezir and Anshal swaps. That said, if the strategy looks sound, I'd prefer to have Duux in my spot as he's the strongest solo-tank healer, which may be important for Vikrum healing in the late stages of the rotation.
Bauser:
I'm fairly certain, rather than mess with three tanks and lose a bunch of DPS, we can get away with only two actual tanks once the stack rotation begins by having Bauser "tank" Anshal when Team A - Nezir / Anshal is on his platform. The reason I think this will work is because even as a DPS spec, Bauser can gain a good chunk of armor/damage reduction just swapping to Blood Presence, which will allow him to taunt Anshal for the brief period Team A is over there. The actual time we spend before going back is very short (~6 seconds), and given the boss will be debuffed by Taka during Team B's turns on Anshal, this should only allow 2-3 swings on Bauser before we fly back to Nezir.
Using the above tables, basically after Wind Chill Cast #2, as Team A - Nezir / Anshal has been hit with stack #2 and is going to Anshal, that's when Bauser will need to taunt Anshal. This means Bauser will "tank" Anshal four times total with the first three being short 6 second bursts and the final fourth as the actual "kill time" where we burn Anshal down, so Bauser's self-cooldowns should be used during that final, kill-shot phase to help me out and also let me spend some of my GCDs throwing ToL Wraths and DoTs on Anshal.
Duux:
You will have to eat the first Rohash Ultimate solo right as we start our rotations, and given you've been on the platform full-time leading up, I hope the Ultimate damage isn't too rough?
Boheem:
Once our rotation begins, like Duux, you will be solo on Rohash's platform, swapping back and forth with Duux between Wind Chill casts. Since we should have Rohash to ~100k before the rotation starts, my hope is you can fairly easily keep yourself alive with a few self-HoTs until the time comes to finish off Rohash, which you'll do solo.