Hearthpwn

You should mulligan the same way in most matchups : Try to curve nice with Fiery Bat into Huge Toad or King's Elekk into Animal Companion / Eaglehorn Bow From then on, you are most likely gonna draw your mid game threats for every turn.

Aggro Shaman is a decent matchup, like a 50/50. It all depends on who gets the early board. If he plays a Tunnel Trogg followed by Feral Spirit and you couldn't contest it, kiss your game goodbye. If you can maintain your early board, and he can't contest it, you'll win.

if you already have a 1-drop, you might want to keep a Quick Shot for an easy removal of Tunnel Trogg, or you can also try keeping a Hunter's Mark for the Flamewreathed Elemental. Snake Trap is also a nice keep against Shammy if you don't have a 2-drop.

Midrange Shaman is a 60-40 on our favor. You just want to take care of their Lightning Storm by not overextending too much, and try to bait their Hex before you play your Savannah Highmane and you'll do ok.

C'thun Druid is seeing some play in high ranked ladder, so you might have some precautions about it. You have to always try to curve well, but if you happen to get a Hunter's Mark in your mulligan phase, KEEP IT, because it will be a huge tempo gain if you can use it on their innervated Druid of the Claw and Dark Arakkoa. Try to keep your minions above 1 health to avoid  Swipe board clear, and you'll be fine. If you achieve to reach midgame and drop your midgame threats, the Druid will most likely have no way to remove, and your way to his face will be clear.

Control warriors are a decent matchup of us. Just maintain control of the board and don't over extend, and you will most certainly win. Care for brawl and also try not to put them to 12 or under unless you need it or you're safe from the buffed Revenge AoE. Keep pressure and he won't be able to stop you in time. Try to bait executes before playing Savannah Highmane or try to play them in an empty board, so you force them to use a spell plus the Execute or even forcing him to hit it with his face :)
Tempo warrior is a tough matchup, maybe the only one which brings real trouble to us, mainly because of Ravaging Ghoul which easily clear our Snake Trap and bring our big cards to Execute range, plus bringing a 3/3 body to the board, and if they combine them with Blood To Ichor it will be difficult to stop the huge tempo gain from them.

Eaglehorn Bow Is an awesome card in this matchup. it gives you means to stop the tempo gain from the warrior, and it's a clean kill for Acolyte of Pain, Ravaging Ghoul and the little slimes. Another great keep is Infested Wolf Because you'll use it after the Ravaging Ghoul is played, and he will likely have to trade, and won't have another AoE to effectively clear the spiders. That's when the Wrangler comes in ( ͡° ͜ʖ ͡°)

Miracle Rogue is pretty popular right now, and the best way to win is by pressuring his guts off. and I mean PRESSURE him. try to put all the pressure you can, always trying to avoid Fan of Knives. With Blade Flurry almost gone from ladder, Rogues have a really bad times dealing with a lot of minions above 1 health (unless the happen to draw Bloodmage Thalnos + Fan of Knives in which case you'll get rekt.
Pressure him enough to bait the Sap on your little minions, so he won't have it for your Savannah Highmane. If he can't sap them, you'll most likely win the game.

If you get the chance to kill their Auctioneer, go for it unless you have lethal, because he can beat you up with 1 turn of drawing glory with it.

There are very few Freezemage/FreezeSaronMage's out there, and they're usually a pretty easy matchup. You want to pressure them a lot, like with Miracle Rogue so they waste their removals early and miss important mana turns like Emperor Thaurissan or miss a Secret or an Arcane Intellect. Denying them their Draw Mechanics is of huge importance to give you time to throw your lategame threats with ease. It's a pretty easy matchup, you can pop their Ice Block with your hero power, which makes it far easier. Try to mulligan your direct damage, you want to draw them in the end game; Get as many minions possible on the board ASAP.

This card is not seen that much on competitive ladder, but I think it's an awesome card given that with the new cards (Specially Infested Wolf) we can almost guarantee having a Beast by turn 5. I found myself very few times where I didn't have a beast to combo my Ram Wrangler, And if you happen to find yourself in that situation, you can always save a Fiery Bat To combo it.
This card played on turn 5 with a beast on board, it's usually an insane tempo boost, and sometimes it just leads to victory by it's own.

This was one of my latest additions to the deck. you DON'T want it as an 1 drop, you want to draw it at your late game, when you have already a really good board, looking for a finisher, or in the midgame if you lost your board, to find a midrange minion and try to recover it. Always try to use it Explicitly when you need it. I can count the amount of times I tracked into a Kill Command, or Tracked into a Call of the Wild and won me the game. This is an awesome card for a midrange deck, and I honestly can't see why such few people run it.