All the other bosses in the instance are pretty cake walk.

For the last boss, spread your guys out around the columns before pulling. Make sure you are within casting range on all of them.
Then Drop your normal totems, For this fight I went 5 healing stream, 4 searing 1 wrath, 1 woa 4 grounding 1 stoneskin and w/e else was on my earth.
Start casting, Put Flame shock on him right away after the LB/CL volley on pull. Put your gifts on the guy he runs to, spam heal him to top him off really quick then start dps'n like crazy.
If he starts casting his frontal cone damage ability "smash". Run all shamans forward, let it finish, then just move them back.

After you kill him first time, top everyone off, drop your elementals, run away so you won't be in front of him for his smash, pop heroism trinkets and go to town.
Kill him first time without any deaths and get to his rez with all your cd's up and your golden.

Took some time and practice with the coordination, but worked out well.
As reference I have about 9k hp, 1300sp 25% crit, 10% haste on the shamans