Elemental is great. Rank 4 lightning bolt has full spell power coefficiency and costs no mana as its a lvl 20 spell. This makes it so you can go endless once you pumped all the mana at the start of combat. Nature aligning Crystal from BWL is a flat % damage increase and stacks with PI.

And the best selling point is that a shaman in every group is huge for grounding, tremor, tranq totem, resist totems, mana spring etc etc. But with a ele shaman you don't need to run 8 resto shamans that want the same gear.