Lol, I did this when my 3 Shamans were level 67-68. But I ran it with a 70 Prot Pally and 70 Frost Mage.
I figured out a good placement and it worked out.

As I enter his room, I start facing 45 degree angle from the left side pillar facing him, and behind the pillar.
Then I would strafe the entire clones (shamans and mage) left and right so I can maintain the 45 degreee position.
When he starts his arcane explosion, I would strafe away and los out of it. Strafing is better than running on follow.
Straffing also allows me to have in in the frontal arc for lightning bolts and shocks / frostbolt and ice lance.

The it was a matter of staggering Water Elemental, and Earth Elemental after each Arcane explosion.

And when I do 3x Chain heal after each Arcane Volley. My lowbies shamans died in the end, but I and the Mage were up to kill him from 15% left.