Mulligans
General Mulligans
The basic cards you want to have if you do not know what you are playing against are aboveAggro Mulligans
Playing against aggro is fun if you get a good early hand. In essence, if you last until turn 6 or 7 (or get Reno/Jaraxxus), you will more than likely win. Each turn, either take out their minions, tap (hero power), or play minions to draw aggro.
Midrange Mulligans
I personally think that midrange decks are the hardest matchup. You have early removal spells for aggro but your midgame is hard since twisting nether cost 8 mana. They will try to unleash their combo on turn 5-6. Have Reno ready so you can heal before they can kill you.
Control Mulligans
Control vs Control usually will be a very long and strenuous game. Here are basic control classes and how to counter them.
Warrior
ISN'T ARMOR THE BEST! You need to deal constant damage each turn so you can keep their armor from getting so high. If you get to the late game, it could go either way. You have 2 major heals (Reno/Jaraxxus) that can both help. To counter warrior, your best cards are Jaraxxus (6/6 for 2 mana), Ragnaros (constant damage), N'zoth (fill the board), and Sylvanas (lemme take your minions).
Priest
Priest likes to steal cards and play spells to remove large minions so play safe and drop semi large minions to get rid of the entombs and shadow words. Like warrior, keep constant damage so he does not heal every turn.
This is the ever popular relock deck with a couple of cards added from one night in Karazhan.
The goal of this deck is to get as many cards in your hand and survive to late game unleash cards such as Ragnaros, N’zoth, and the Curator!
Here are the cards I subbed in and why I did.
Prince Malchezzar
This card fits so well into this deck. It adds 5 legendaries to your deck so you now start out with 35 cards which is huge for Renolock considering one of its biggest weaknesses is milling yourself.
Corrupted Seer
I put this card in just for Curator. It’s a 6 mana 3/3 2 damage to all non-murloc minions which is not great but helps with removal. If you were to remove it, I would sub in more healing for it.
Moat Lurker
I might be giving this card more hype then this deserves but I went ahead and added it. Any card with death rattle will be so good with this card (Sylvanas, Cairne). It also can be used on a damaged Ragnaros or anything that had power overwhelming on it (usually resulting in it dying at the end of turn). It can also be used as a temporary removal for enemy minions (but it will be resummoned unless you silence it). It also has death rattle so it will come with N’zoth (but the death rattle wil not carry over sadly). It is easily countered by entomb, silence, polymorph, hex, mind control, or anything that prevents it from triggering the death rattle.
The Curator
Adding 5 cards to your hand makes finding certain cards harder than ever before. This card can help by giving you 2 removal minions (Stampeding Kodo and Corrupted Seer) and a Dragon that can have up to 10 health (MAKE SURE YOU PLAY THIS CARD FIRST TO GET FULL VALUE). This card could mess up if Prince Malchezaar puts a legendary Dragon, Beast, or Sir Finley your deck (R.I.P. Old Murk Eye) and it draws those instead.