My guild, <Reagan Smash> on US-Malygos got out server first kill on this guy last night (and are one of the first 5 guilds in the world to get the achievement; Share the Pain) using a strategy that, well, basically makes the fight a no-brainer.
What is required to make this strategy work;
SHADOW PRIESTS! - Atleast one, preferably 2 (10 man)
How this strategy works;
Throughout the boss fight, pink colored crystals will spawn and attach to the closest player via a 'laser beam' as I like to call it. The goal for this strategy is to let your shadow priest(s) take as many stacks of Torment as possible in order to give your healers as many stacks of the healing buff as possible at the very beginning of the fight when tank healing is fairly simple. We had 2 shadow priests in our first 10 man kill and they were both able to stay on one crystal for its entire duration (25 stacks of Torment). The hardest part about this strategy is timing your shadow priests timing their dispersion so the 25th tick of Torment doesn't kill them.
It's probably worth noting that we used 5 people in a 'rotation' to handle all the crystals, this is how we worked it.
Crystal 1 - Shadow#1 priest takes 25 stacks of Torment using dispersion.
Crystal 2 - Shadow#2 priest takes 25 stacks of Torment using dispersion.
Crystal 3 - 3 dps rotate on this crystal, the first two dps taking 9 stacks of Torment and the 3rd dps getting 7 stacks.
Crystal 4 - Shadow#1 priest takes 25 stacks of Torment using dispersion.
Crystal 5 - Shadow#2 priest takes 25 stacks of Torment using dispersion.
Crystal 6 - 3 dps rotate on this crystal, the first two dps taking 9 stacks of Torment and the 3rd dps getting 7 stacks.
If your shadow priests are using Glyph of Dispersion that cycle can continue until the boss is dead, which is actually unnecessary once your healers have 100-125+ stacks of Vital Spark. Our 3 healers ended the fight with just under 200 stacks of Vital Spark.
What needs to happen;
When a crystal spawns have one of your shadow priests go stand next to it. Healers will need to constantly be healing this person while they are healing the tank (which is why it's best to focus on this strategy early into the fight when tank healing is easy). As soon as your shadow priest hits 19 stacks of Torment they will need to use dispersion (or they will probably get one shot). If they time it properly their dispersion will last until the crystal has despawned. If you have more than one shadow priest in your raid then repeat this for the next crystal as well.
Our shadow priests were both able to take 25 stacks of Torment off the first 2 crystals, which made our healers end up with ~100 stacks of Vital Spark, so when they switched over to healing the tank the could use smaller, more mana-efficient heals such as Holy Light and Heal to keep the tank alive.
I'll post our kill video once we get it uploaded.
---------- Post added 2011-06-30 at 01:04 PM ----------
Kill video: http://www.youtube.com/watch?v=1RQCpCsAb34
Apologies for the sound quality at the very beginning of the video.