I decided not to use MF because in 99% of the cases I would end up overaggroing and killing myself due to overkill aoe damage. This is in 25m though, so idk if you have less adds but I would presume that to be the case. I specced Destro or Demonology for this fight, and both worked. I also had problems with my pet dying, so GoSac helped a lot. Especially as destro with a heavy mastery build.
If you wanna go affliction, you can try
Seed > SB: Seed > SB:SS > SS inhale immediatly
SS exhale on another mob, SS inhale immediatly. Rinse and repeat.
You should be applying 2 seeds and 3 dots in 2 GCD
Played affliction, slow is nice for early split phases if you're struggling and the boss damage is second to none. If your raid really needs hard AoE to bring the adds down I'm sure either demo or destro will do the job fine, but you'll lose a lot of boss damage.
I glyph coex - affi - 25m, ymmv - not sure how many adds 10m gets.
1) dps boss/sbsoc the aoe pack with 2fps.
2) when adds spawn I find the biggest group of adds near each other and press soulburn coex macro for a nice slow moving pack.
2.1) Save shadowfury for saving whoever screws up their cc and is going to leak.
3) /dance till till immerseus respawns. You can sbss / slowswap around if you want, and malefic grasp, but this bit kinda sucks, unless you have nice dps buddies who will let you kill some on your own.
4) Cry that the ele shaman has more epgp, and you don't get h tf bindings.