I'll copy paste what I wrote on my guild forum :
This Heroic mode is probably the 2nd easiest and is likely the 2nd Heroic boss we will try.
ScrubBuster's vid : (Ele Shaman PoV)http://www.youtube.com/watch?v=3WSLddAHSXY
By bouncing you gain stacks and when the ball hits the boss those stacks result in more damage taken, which I believe is for the entire fight. Therefore you want to bounce the ball as much as you can without killing anyone.
ScrubBusters did the following:
1st : ranged group (replaced by a Shadowpriest or Fire Mage when it's phase 1 again)
2nd : melee group (ranged moving out to sides)
3rd : Shadowpriest with Dispersion (glyph it)
4th : Entire raid in melee
5th : Shadowpriest with Dispersion (possibly external cd as well)
6th : Entire raid in melee
7th : Fire Mage (triggering Cauterize)
8th : Entire raid in melee (probably with cd)
9th : Fire Mage (triggering Cauterize)
10th : Boss (everyone needs to make sure they aren't near the ball)
Blood Legion kept the raid split in 2 groups and just healed through. I like ScrubBusters's tactic more because it's less mana intense for healers but you lose a bit of dps due to ranged having to move a bit.
In phase 2 they did dps down eyes. We ignored them mostly on PTR but maybe they adjusted their damage. The 2 big tentacles and the 4 Flails have to go down tho. Split the raid and everyone dps's down their add. If needed, ranged can dot up the other adds as well.
During the fight you may get the debuff called Disrupting Shadows. If you dispel it, it causes a knockback and AoE dmg. Because this is only dealing healable shadow damage, ScrubBusters did NOT dispel it. If you want to dispel it, like Blood Legion did, we need an addon that marks all players with the debuff. Then healers need to manually check if their marked target has run out of the raid and dispel it. Assigning healers to groups may help there.
This fight is not hard on tactics but it is on the execution part. If the people that need to bounce die too early it can be a wipe before anyone has time to react. Also, if we need to bounce it to the boss and people are bouncing it back, it will kill a lot of people making it an auto-wipe.
Anyways, that's for 25. In 10 man, you can't stack that many Mages and Sp's probably so I have no idea how that would work.