After almost one-shotting the entire fight on our first attempt before being foiled by a dc'er, we ended up spending the rest of the night wiping to the same spot in the fight. Fourth platform on the very first Elementium Bolt that spawns after Nozdormu's buff is canceled out.
As a guild who spent about 3 months working on Heroic Ragnaros before this tier, we're almost completely 391s (besides one recently recruited member who is mostly 378s). We should be completely overgeared for any and all aspects of this fight.
Running 2 tanks, 3 healers, and 5 dps. The order of buffs that we kill off was Ysera, Alexstraza, Nozdormu, Kalecgos, thereby ensuring that the Elementium Bolts didn't deal any raid damage whatsoever until the last platform. Our issue is once we GET to that platform, no matter how we react to the bolt it causes fundamental issues that are not dealt with in guides (presumably the guides were made in PTR where the fight is, again presumably, undertuned).
We tried stacking everyone at the front side of the platform by the Limb Tentacle as the maximum possible range from the Bolt with a Power Word Barrier and Aura Mastery. The issue with this is when the Elementium Bolt spawns, despite EVERY dps in the group burning down the Mutated Corruption from the moment it spawns it still has a good 5 to 6 million health at this point, therefore a tank is still needed to be near point blank to the Monstrosity while damn near the Elementium Bolt at this same time. There is a huge RNG factor with this that is also noticed, as half the time Impale is being used at the same time the Elementium Bolt is still alive creating an impossible situation. The other half the the time when Impale and the Bolt are off set in a way that makes it possible, Impale is used just seconds before the Bolt reducing the tank's health to dangerous levels right before the impact. Even with saving all cooldowns for the tank at this moment, its still a 50/50 chance whether or not he'll be killed by this process or survive it with less than 20k health in a situation he's potentially completely out of range of heals for. Our best attempts on this fight were mere lucky chance the tank ended up surviving thisand letting us proceed with the rest of the fight, but that was only about half the pulls that we tried with this strategy.
We tried stacking everyone up at the opposite of the platform near where the aspect is, thereby being able to include the tank IN the Power Word Barrier being used and making sure he's within range of the healers at all times. With this strategy we've tried both spreading out after impact and burning down the Bolt while remaining stacked up, and both ways we get spiky deaths from the ensuring Crush from the Corruption. If we're stacked up it hits the raid and causes at least 1 to 3 people to randomly die, and if we spread out it still instantly kills whoever it inevitably targets. Pulls with either variation of this strategy always failed to beat the soft enrage of Cataclysm due to dead dps.
We have not tried 6 dps and 2 healing this fight yet, and I am only half-sure that would even change anything (5-6million health is alot for only one other dps to be able to kill; and although the extra dps would be able to guarantee that last tick from the Bolt wouldn't go off, the lack of heals would make the initial impact cause more spiky deaths).
I am sure there's some fundamental thing that's incredibly obvious that we missed or that we're not doing, but there just isn't that much info on this fight yet and we've been bashing our heads against it for too long.