Hearthpwn

I had been experimenting with quest evolve shaman this expansion, but I realised the games I won were usually not through quest value but Boggspine Knuckles tempo. So I rebuilt it as a deck that's looking to create massive board swings around turn 6/7 and close out the game. It works really well, I went 16-6 to legend last season, then 19-5 to legend this season!

(Larger sample stats for my previous build are now available on HSReplay and it was showing 55% WR in Diamond and Legend - https://hsreplay.net/decks/jqeryYnpj55JrMH7NAD8vb/#rankRange=DIAMOND_THROUGH_LEGEND )

And the best part is it's not an expensive deck at all. Maiev and The Lurker Below are the only legendaries I'm running, and both are replaceable (though Maiev at least is very good, in this deck and generally). More discussion on replacements below.

The main win condition is to equip the weapon on 5 (or 4 with coin) , play free Dread Corsairs and swing to evolve them into 5 drops, then next turn play Desert Hare hopefully with Mogu and swing again to get a giant board, creating overwhelming board tempo against aggro and threatening Bloodlust lethal against control. Carefully plan your overload cards because you rarely want to delay playing the weapon.

Remember that this is not a straight up curve deck where you're trying to vomit out your hand. Especially against control, you need to play to swing turns. Don't just slam your Desert Hare if you have the weapon in hand. Three 1/1s on turn 3 are very likely to get cleared, but three 4 drops on turn 5 or 6 are much harder to deal with for the current suite of board clears in standard. It might be better to freeze/Maiev an opposing minion rather than clear it if that helps you play Mogu Mutate the next turn. Sometimes it's better to hold a lackey and float 1 mana if you think you need to activate Weaponized Wasp the next turn. Plan ahead!

Mulligan guide

The power card of the deck is Boggspine Knuckles, it's very difficult to win without drawing at least one, so mostly that's what you're looking for in the mulligan against every deck. If you have Knuckles you want to keep synergy cards like Desert Hare, Dread Corsair and Mogu. You probably want to keep 1 drops against aggressive decks. Mogu+Mutate is also a combo worth keeping.

Against AoE focused classes like Demon Hunter, Warlock and Druid you want to prioritise Mogu, while against single target removal focused classes like Rogue you want to prioritise Desert Hare.

Card replacements

When replacing cards, you want to think about what kind of decks you are mostly facing/are popular based on meta reports. If it's a lot of aggro, you want to cut greedy cards for better early game and tempo, but if it's a lot of control you want to switch low value cards for higher value/more burst. Pay attention to the curve though - you don't want to pass an early turn so don't cut all your 2-drops for example. For this, you can't just go by mana cost of the card alone, you have to think of what turn you want to play that card. You can't play Desert Hare before turn 6, Weaponized Wap is often a 4-drop because you need to play a lackey with it, Hoard Pillager is a late-game value card etc.

Against aggro: you can cut a copy of Hoard Pillager, Evil Cable Rat (not a great card in any matchup, but you need at least one copy to support Wasps), Bogstrok Clacker. You can put in Serpentshrine Portal, Surging Tempest, Storm's Wrath, Stormforged Axe (especially great against demon hunters, but remember to cut Hoard Pillager), Imprisoned Vilefiend.

Against control: you can cut Imprisoned Vilefiend, Frozen Shadoweaver, The Lurker Below. You can put in Bloodlust, Escaped Manasaber, Gnomish Inventor, Swampqueen Hagatha.