Check my thread for timings and reference
http://www.mmo-champion.com/threads/...-Spark-soakers
1 DK 2 Holy pally 3/4 Spriest 5/6 Spriest - Transition - 1 Spriest 2/3 SPriest - Transition - Repeat of last --
With the above, you would cc (hex + sheep) the 3rd & 5th rages then kill them together with the 4th and 6th. You need to cc the 4 so they die together. Your killing priority is as follows, courage > rages > strength > boss. The Warlock should slow the Courage before it puts up the shield.
For reference, when you stand next to a spark it will explode but will not damage immediately. This means the following:
Warlocks can soak with teleport every 30 seconds per 1 spark. Druids can soak with symbiosis teleport every 30 seconds from Warlock. Mages can soak with Blink every 15 seconds. Mages can soak with iceblock. Warlocks can soak dbl sparks (but not 4) with DB + UR. Holy pally can soak every 5 minutes, priest every 2 minutes. Rogue can soak at any time provided they can melee a mob beforehand for Feint with Elusiveness. Elemental shamans are not advisable for soaking, even with their CD.
I would personally suggest using immunities to soak as much as you can, it lowers the damage taken on this fight by such an obscene amount.
There is a key reason we CC those rages by the way. Notice from the timings the courage spawns ~ 15 seconds after the 5th rages. We never managed to kill those rages fast enough AND get to the courage in time, meaning either the tank ends up getting raped or the raid does. It's far easier to just kill them with the last set of rages & focus on getting the courage down in time.