The basic strategy is to multi-tank to counter the mem-wipe, max-out poison resist, and make sure the rest of the raid foce avoids the frontal AoE's by standing under his rear legs. Also, be sure to group cure noxious to get rid of the Soul Evisceration, otherwise you'll be hit by the other AoE.

He also spawns adds during the fight that must be dealt with. One of his AE's will spawn an add (Soul Evisceration) if it hits a dead body in the raid, so make sure you rez people ASAP.

Finding a good spot to tank him the water is preferred to deal with his knockback. Positioning him is the trickiest part of this encounter due to his large size.