The current shamans deck gets most of its power from a single card: Offering Yard Priest, and then other cards that recycle him. ie, Reanimate and Swamp God Emissary.
I'd like to suggest changes to a few cards, with the goal of splitting the power of the shamans archetype across several good cards (including a new card). This instead of focusing it all in the currently busted swifted Offering Yard Priest. At the same time these changes can help make the deck's matchups less polarized, allowing for player decisions to have a higher impact on the outcome of the match, instead of mostly what deck it queued into. Keep in mind that the goal of these suggestions ins't necessarily to nerf the shamans archetype.
I'd like to change Totem of Swiftness, Offering Yard Priest, and then introduce a new good shaman card as well.

With this version of Totem of Swiftness you can't easily swift out creatures with incredibly high attack anymore.

This version of Offering Yard Priest gives the shamans archetype more defensive power. He can block 2 creatures, and he cannot be pinned by an attacker. Example, if 1 creature is attacking him, he must block that creature regardless of its speed, and may still block another creature. If 2 creatures attack him, he must block them regardless of their speed, and he may not block any additional creatures, as he is already blocking 2.
With these changes, we can print another good shaman card:

These things combined would turn the shaman archetype into a more midrangy value deck, rather than a very slow to start up but extremely powerful swift-to-kill deck.