Hearthpwn

Mulligans are very similar for different decks as you are mainly looking for Doomsayer, Bluegill Warrior, and Truesilver Champion. On the odd matchup you may want to keep Aldor Peacekeeper in case of Flamewreathed Faceless or Animal Companion if you do not have Truesilver Champion in your hand.

1. Warrior: Overall, when playing against warrior you are going to want to keep Doomsayer and Trusilver Champion. Both of these cards provide answers to early game minions and help you to keep a safe board.
Against...
Control warrior- Keep Bluegill Warrior to use murlocs early and immediately start preparing for Anyfin Can Happen, Doomsayer to be able to set up the board for a turn 5,7 or 8 minion, and Stampeding Kodo to counter Bloodhoof Brave.
Tempo Dragon Warrior- Keep Bluegill Warrior for early murlocs and clear, Doomsayer for board clear, and Trusilver Champion for more clear.
N'Zoth Warrior- Keep Bluegill Warrior to use murlocs early and immediately start preparing for Anyfin Can Happen, Doomsayer to be able to set up the board for a turn 5,7 or 8 minion, and Azure Drake to provide cycle through the deck and a minion on board.
C'Thun Warrior- keep Doomsayer to clear board or absorb 7 damage from early C'Thun Minions, andTruesilver Champion to clearn early C'thun minions such as Beckoner of Evil and Disciple of C'Thun.

2. Shaman: Overall, when playing shaman you want to keep Doomsayer, Aldor Peacekeeper, andTruesilver Champion to remove minions and not get rushed down.
Aggro Shaman- keep Doomsayer, Aldor Peacekeeper, andTruesilver Champion
Mid-range Shaman- Doomsayer, Bluegill Warrior , andTruesilver Champion
Bog/Control Shaman- keep Bluegill Warrior, Murloc Warleader, and Aldor Peacekeeper

3. Rogue: Overall, you want to keep Doomsayer to clear and absorb damage along with Truesilver Champion for more removal.These mulligans go for all rogue match-ups.

4. paladin: Overall, you will most likely play a mirror match-up or N'zoth deck. This will require you to mulligan for Doomsayer to clear minions , Truesilver Champion to clear minions and Azure Drake or Solemn Vigil to provide card draw. These mulligans go for all paladin match-ups.

5. Hunter: Overall, hunter is the worst match-up but i recommend keeping Doomsayer, Bluegill Warrior, Aldor Peacekeeper, Murloc Warleader, Keeper of Uldaman, or Truesilver Champion. These mulligans go for all hunter match-ups.

6. Druid: Overall, you want to keep your murlocs, Truesilver Champion and Consecration if they use Violet Teacher into Power of the Wild. These mulligans go for all druid match-ups.

7. Warlock: I would be surprised if you play any warlock other than zoo. When playing zoo you need to keep Doomsayer, Consecration, Truesilver Champion and maybe the pyro + equality combo if you have it.

8. Mage: Overall, you want to keep your murlocs, Doomsayer and Truesilver Champion.
Tempo mage- Keep your murlocs, Doomsayer, Truesilver Champion and maybe Consecration depending on if you have anything to deal with Sorcerer's Apprentice or Cult Sorcerer
Freeze Mage- Keep you murlocs, Truesilver Champion and Azure Drake or Solemn Vigil to provide card draw.
Control Mage- Keep your murlocs, Doomsayer and Truesilver Champion for removal.

9. Priest: Overall you want to keep Truesilver Champion, Azure Drake or Solemn Vigil.These mulligans go for all priests.

1. Warrior...
Control Warrior: Continue to set up board with minions from your hero power and put pressure on the warrior. Try to get murlocs out early and use Anyfin Can Happen as soon as you can.
Tempo Dragon warrior: Try to remove everything on board efficiently. Continue to heal and stay alive until they run out of cards. Use Anyfin Can Happen when you can and keep at the same speed as the warrior.
N'Zoth Warrior: Continue to set up board with minions from your hero power and put pressure on the warrior. Try to get murlocs out early and use Anyfin Can Happen as soon as you can.
C'Thun Warrior: keep at the same speed as the warrior and monitor the size of C'thun. Stay at a reasonably high amount of health on turn 10+ and use Anyfin Can Happen as soon as you have both and at least 2 Bluegill Warrior and 1 Murloc Warleader has died.

2. Shaman...
Aggro shaman: clear board efficiently and keep health reasonably high (20+ if possible) in order to avoid burst. The main goal is to burn them out and wait till they have no cards in their hand.
Mid-range Shaman: Clear board efficiently and monitor his totems from turn 7+ in case of Thunderbluff valiant. IMPORTANT TO MAKE SURE your murlocs die and are not Hexed. Include them in Pyro + Equality combo if you need to.
Bog/Control Shaman: Nullify and clear minions. Use Anyfin Can Happen as soon as possible.

3. Rogue...
Tempo Rogue: remove minions efficiently and try to stay above 20 health if possible in case of spell burst.
Burgle Rogue: remove minions efficiently and stay at the same pace as opponent.
Miracle rogue: Remove important minions such as Gadgetzan Auctinoneer before they get too much value and keep at a high health.
Malygos Rogue: Remove any kind of spell damage as soon as possible and try to keep at 29 health exactly. This prevents your opponent from shadow striking face for 5 or 10 with Malygos.

4. Paladin...
Anyfin (Mirror Matchup): Try not to play any murlocs as they also work towards your opponent's Anyfin Can Happen. you want to try and keep the board to yourself at all times. By this i mean, play things like Azure Drake or Keeper of Uldaman to get your opponent searching for answers. Life is key in this match-up and if any murlocs do get played you have to keep track of the damage Anyfin Can Happen can do. Save Aldor Peacekeeper and Stampeding Kodo for Tirion Fordring or Ragnaros, Lightlord if need be.
N'Zoth Pally: deathrattle is your worst friend. Anything with deathrattle you want to usually trigger it before clearing board with Equality combos. Keep track of your health and murlocs played in order to stay alive and play the Anyfin Can Happen as soon as possible.

5. Hunter...
There are many different types of hybrid hunter decks out there and they are all very bad match-ups. The main goal for all of them is to try and stay alive. Sounds simple but it's not.In order to do this you will need to keep at the same speed as the hunter and make very smart decisions on when to clear board and what to clear on board first. If you make these decisions correctly and save Aldor Peacekeeper for Savannah Highmane you should be able to slowly take control of the game.

6. Druid...
All standard druid decks are very similar in what they run and they all have the same goal when playing against them. The goal is to play murlocs for early pressure while they ramp, ALWAYS remove Fandral Staghelm as soon as possible, and remove big minions efficiently. You want to try and save Aldor Peacekeeper for Arcane Giant and stay above 20 health in case of malygos.

7. Warlock...
The only warlock deck being played is zoo. Your objective is to remove board as efficiently as possible. Use Doomsayer and Consecration to their fullest potential. On the odd scenario where you play reno or some other warlock deck play it as you would with any other mid-range or control match-up. Maintain board and put pressure if possible.

8. Mage...
Tempo Mage- try not to get bursted by spells. Remove minions as soon as possible without wasting cards like Consecration on one minion. Your biggest threat is Fireball so use healing cards to stay above 20 health if you can.
Freeze Mage- Try to use murlocs early, keep as much health as possible but remember to save forbidden healing when Alexstrasza is played. Use Anyfin Can Happen when you are able to pop the Ice Block and keep pressure throughout the game to try and lure out some of you opponents burst.
Control Mage- Similar to freeze mage you want to focus on using Anyfin Can Happen to pop Ice Block but you also need to clear board more often in this match-up as your opponent may have minions like Azure Drake that you don't want doing too much damage to you and combo with their spells. IMPORTANT TO MAKE SURE your murlocs die and are not polymorphed. Include them in Pyro + Equality combo if you need to.

9. Priest...
All of the priest match-ups are very similar in the sense that you want to cycle through your deck for combo and worry less about clearing board because priests won't do too much damage and won't have any burst at all. THE MOST IMPORTANT THING is to make sure your murlocs die and don't get entombed. You want to charge Bluegill Warrior into minions and include Murloc Warleader in the Pyro + Equality combo. Besides that your goal is to focus on getting a good Anyfin Can Happen as early as possible and only clear board or heal if you are being pressured.

Highly Favoured Match-ups:
Warrior

Favoured Matchups:
Shaman
Mage
Rogue
Druid

Even Matchups:
Paladin
Priest
Warlock

Unfavoured Matchups:
Hunter

Both these first two cards are very important and are hard to find replacements for. if you are missing both in your collection then you will need to craft atleast one to make the deck playable but both are kinda needed.

1. Ragnaros, Lightlord replaced for Forbidden Healing, Ragnaros the Firelord, Alexstrasza

2. Tirion Fordring replaced for Forbidden Healing, Ragnaros the Firelord, Alexstrasza

3. Solemn Vigil replaced for Loot Hoarder, Acolyte of Pain or Harrison Jones

4. Keeper of Uldaman replaced for Stampeding Kodo, Loot Hoarder or Barnes

5. If you really need to replace Anyfin Can Happen i recommend using X2 Wisp