Look in the sky!
It's a Pringle!
It's a pancake!
It's a healer essence called the Well of Eternity!
Didn't realize people didn't know what was floating around 
pic.twitter.com/S7yammbVBH
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that transmog though
is it a set or separate pieces?
Chest is exclusive to shamans from their class hall in Legion and the weapon is exclusive to resto shamans as their hidden artifact appearance in green variant from Legion. Those are the only two I think that "might" be considered part of a set.