So first off, this is a modified deck that I saw on another site, and I really enjoyed it, so just wanted to share. I pushed from D4 to Legend with it over the past week, with a few Highlander Hunter games in there as well. I don't have much statistical insight here, but I can say that it was my best shot against heavy aggression like Face Hunters and Stealth / Weapon Rogues. Demon Hunters were sometimes difficult with their massive damage swings, but manageable with some healing available. Additionally, I was able to out-control some Priests and fatigue them down.

DEFENSE is the theme here.

For aggro, you really want Lightning Storm available in the mulligan, and I would try to get some value out of it, especially to knock out a few stealth guys against Rogues. Side note, I wish Blizz would update this card to just overload for one mana, I think that would be perfectly reasonable. Shaman needs help for fuck's sake.

It's ok to tempo out Marshspawn if you need some board presence. But Serpentshrine Portal on 3 and Marshspawn on 4 is really nice when you have it available.

A good trick to create more healing is the Diligent Notetaker + Witch's Brew combo. And remember to drop a totem before Tidal Wave to get that extra 3 health if needed, maybe you get a spell damage totem and heal for more.

Against Paladin, you want your transform cards at the ready for sure (Devolving Missiles, Hex). And get some extra value with Diligent Notetaker. Cut off those Libram buffs fast, especially to limit their usage of that goddamn Pen Flinger.

And remember that you have a guaranteed Reliquary of Souls with The Fist of Ra-den and a 1 mana Torrent or Devolving Missiles, so you can create more healing that way (and extend your deck with multiple copies).

Be mindful of your overload, so you don't lock yourself out when you really need that Walking Fountain or Tidal Wave on 8.

King Phaoris is mainly for fun, but he is actually impactful in grindy control matches after you have baited out your opponent's removal.

Most losses were really due to not drawing the healing that I needed. So you could try to augment that if you have issues. But overall, I just really enjoy Shaman and it was a fun accomplishment to hit Legend with such a maligned class (maligned at the moment anyway!)

Cheers, have fun guys!