tefrin

Ele shaman is sustainable through long fights but you need right gear and bufs. 6k mana unbuffed at least and all int buf you can stack. Mana saving/free cast/ regen trinket and a good potion rotation. Being in grp with resto shaman helps alot too. Use LB only, shock/CH cost too much. Maybe even start the first phase with lower rank LB and save top rank for nukephase or when you know the tank has enough aggro to hold your continous crits. Drink after dropping totems and know your class!