4. Eternal Sentinel
As the Faceless monster above has proven, Shaman is in a great place for the next expansion. I thought of highlighting their spectacular cards like Hallazeal the Ascended or Master of Evolution, but I think the thing that Shaman decks really lacked was a way to mitigate their Overload. Now they can easily play massive overload cards like Elemental Destruction, or even moderately priced ones like Feral Spirits, and with both Eternal Sentinel and Lava Shock in Standard, they will almost always find a way to mitigate their Overload.
