Hearthpwn

You should always keep Reno Jackson, Doomsayer, Twilight Drake and Mountain Giant because of how important and valuable they are in the early game.

Doomsayer is always good to slow the game down as it essentially freezes a turn by either soaking up 7+ damage or valuable removal such as a Hex or even a Mulch.

Twilight Drake and Mountain Giant are cards that are really good to get out at turn 4/5 since they contest the minions that Aggro decks are pumping out as well as putting pressure on the slower Midrange/Control decks forcing them to use important removal off curve such as Shield Slam + Execute, Mulch, several Druid spells, Sap etc.

Reno Jackson is kind of a no-brainer, essential against Aggro decks since it can completely turn a game around when the opposing shaman/hunter/warlock has run out of steam and resources completely making it gg when you heal up for 20+ hp with a 4/6 on board.

More class specific mulligans are included in the matchup guides.

Currently the most played class on ladder since the midrange variant is the most broken thing there is right now with early game cards such as Spirit Claws, Tunnel Trogg, Totem Golem and Maelstrom Portal making it able to out value the slower control decks as well as having the ability to efficiently trade and rush other aggressive decks.

CLASS SPECIFIC MULLIGAN: Hellfire, Imp Gang Boss and Shadow Bolt. Great cards to stall the game with, Hellfire is great against shaman since it kills every early game threat Shaman has with the exception being Totem Golem. That's what Shadow Bolt is for, being able to remove Totem Golem, Mana Tide Totem, Azure Drake or even a Tunnel Trogg if its snowballing too hard.

GAME PLAN: Your general game plan is to avoid taking damage at all costs. You do this by playing strong minions on curve (Twilight Drake, Mountain Giant etc.), using AoE (Hellfire, Demonwrath, Shadowflame, Baron Geddon, Twisting Nether) efficiently even if it involves wasting Power Overwhelming to make a good Shadowflame possible. Simply stay alive until you need/are able to play Reno Jackson.

PLAY AROUND: Bloodlust !!, Lightning Storm, Thunderbluff Valiant, (Hex) hard to play around some times since you will have to play on the off chance that they don't have it in order to stay alive and react sometimes, forcing your opponent to use a Hex turn 5/6 can also be good since they more often than not lose tempo by doing so.

Zoo aims to play cheap and strong minions (Flame Imp, Imp Gang Boss, Dark Councilman, Dark Peddler etc.) on curve to establish a strong board presence which they then use to push face damage with.

GAME PLAN: Same as Shaman, Don't let them establish a strong/big board !!

CLASS SPECIFIC MULLIGAN: Same as Shaman with the addition of Mortal Coil

PLAY AROUND: Doomguard, Doomguard + Abusive Sergeant, Soulfire, Soulfire + Abusive Sergeant. Play around anything that can kill you depending on how large their hand is, how much mana they have, how many outs (damage options) they have remaining etc.

Hunter decks play the value game, play strong minions on curve like Cloaked Huntress which also allows for big swing turns since it makes Secrets cost 0 instead of 2.

GAME PLAN: Board presence is key, one of the big win conditions besides Reno Jackson is having at least one big taunt in play to soak up damage and removing minions, that's why Twilight Drake and Mountain Giant are key cards in this matchup as well as Doomsayer and Reno Jackson of course.

CLASS SPECIFIC MULLIGAN: Same as Warlock

PLAY AROUND: SECRETS!! The big thing about Hunters in this meta is their secrets and these have to be played around at all costs at all times to not get completely screwed over (and overly BM:d). For example never attack with a taunt/what is to become a taunt unless you 100% know that they don't have Freezing Trap. Don't use spells unless you're forced to since you don't want to proc Cat Trick (only use spells if you then have a way to deal with the Cat that gets spawned). Then of course play around the basic Kill Command, Quick Shot, Eaglehorn Bow and Houndmaster. Aim for the long game, deal with their stuff, play around damage and wait for Reno Jackson.

Rogue is a reactive deck with lots of cheap reactive cards and removal like Sap, Backstab, Shadow Strike, SI7: Agent, Gadgetzan Auctioneer,Edwin VanCleef etc. which they use in order to gain tempo and then snowball that tempo into a winning situation.

GAME PLAN: Play conservative and be the reactor. Remove their threats as efficiently as possible and only play minions when you either have to or when you feel like you will put the Rogue in an uncomfortable/unfavorable position.

PLAY AROUND: Sap !! You don't want to make the mistake of having a minion on board with 9 cards in hand at the end of your turn, that then gets sapped and you end up discarding something like Reno Jackson or Ragnaros the Firelord because of your hand being too full. Other than that you should also be playing around Malygos + 2x Sinister Strike (16 dmg), General removal spells as Backstab, Shadow Strike, Sap, Eviscerate etc.

Since there's two varieties of Mage on ladder right now (Freeze and Tempo) I will try to cover them both.

GAME PLAN:

Against Freeze Mage: You need to get stuff out on the board, fast. Your goal against Freeze Mage is to force them to play reactively and waste their removal and burn on your minions instead of your face. A turn 4 Mountain Giant is the best case scenario since it will start putting in a lot of damage face really early. Ragnaros the Firelord is also key in the matchup as it deals damage even though it can't attack. Never try to outlast the Freeze Mage cause you won't win that battle. Race them and try to end as fast as possible while still playing around cards like Doomsayer by saving Siphon Soul and/or Shadowflame to be able to deal with it.

Tempo Mage: Play the Survival game, deal with their minions with AoE or single target removal such as Shadow Bolt, put up big taunts and then drop Reno Jackson to seal the deal.

PLAY AROUND: SPELLS !! This applies for both archetypes as both of them have the ability to burst you down from high health totals. Therefore its important to keep track of what spells have already been used as well as the highest total damage they're able to deal having their hand size, remaining cards and mana pool in mind.

CLASS SPECIFIC MULLIGANS: Shadow Bolt (to be able to deal with threats such as Azure Drake and Flamewaker) and Hellfire (to be able to clear the early minions Tempo Mage can pressure you with)

Assuming it's control Warrior (which is the type of Warrior deck that is the most popular on ladder right now). Warrior aims to stall the game by removing threats efficiently with cards as Execute, Shield Slam and Brawl. They try to stall the game to the point where they can just "outheal" you with their hero power.

CLASS SPECIFIC MULLIGANS: Emperor Thaurissan to guarantee the post turn 6 tempo swing and combo enabler.

GAME PLAN: Pressure the Warrior by putting out minions without overextending that they have to waste their removal on. Never have more than 2 minions on your side of the board at a time to force the warrior into using a badBrawl.

PLAY AROUND: Execute, Shield Slam, Brawl and Grommash Hellscream.

Should be an easy win if set up correctly. Use the same play style described in the Warrior section.

CLASS SPECIFIC MULLIGANS: Emperor Thaurissan to ensure the 20 damage combo early on as well as the post turn 6 tempo swing.

GAME PLAN: Same as Warrior

PLAY AROUND: Equality + Wild Pyromancer/Consecration, same tactic as against Brawl, don't overextend, try to keep as few minions as possible on board.

Druid is also a good matchup for this deck since they play very conservatively allowing us to set up our 20 damage combo as well as being able to take care of their threats like Malygos, Fandral Staghelm, Ancient of War and Arcane Giant with cards like Spellbreaker, Siphon Soul and Twisting Nether.

CLASS SPECIFIC MULLIGANS: Shadow Bolt (to be able to combat a possible Azure Drake) and Emperor Thaurissan (to be able to enable the 20 damage combo as early as possible)

GAME PLAN: Get stuff out on the board as much and often as possible and trade efficiently since Druids can't really take care of it at all since a lot of Druids have decided to cut the Mulch from their lists making Mountain Giant and Twilight Drake insane cards in the matchup.

PLAY AROUND: Malygos + 2x Moonfire and Fandral Staghelm with about anything that has a combo effect.

Most priests are playing some kind of "ressurect" deck with Injured Blademaster and Onyx Bishop. Since this deck is too inconsistence it shouldn't be a hard matchup unless they get an insane opening.

CLASS SPECIFIC MULLIGANS: Shadow Bolt (for trading) and Emperor Thaurissan (for enabling the 20 damage combo as early on as possible)

GAME PLAN: Get stuff out on the board and make them stick as well as trading with their minions efficiently to avoid being outvalued/outhealed by the Priest which can be devastating if not respected.

PLAY AROUND: Shadow Word: Pain, Shadow Word: Death and Entomb. Don't think I need to go in on that one more than that.

Will be updated when someone asks for a card replacement

Baron Geddon: Replace him with Chillmaw or Corrupted Seer for the AoE they offer

Demonwrath: Replace with Drain Life, Horserider or Corrupted Seer

Gameplay by Fur0: