DISCLAMER: THIS DECK WAS MADE FOR HAVING FUN AND NOT FOR REACHING LEGEND
This deck should always beat ramp Druid and performs well with a good draw against aggro Demon Hunter, pirate Warrior and both mech Paladin and Mage. Against control Warrior you will need to ensure that you pair Ambassador Faelin with Brann Bronzebeard to keep up with their custom deck of treasures. You should also try and use Mutanus the Devourer to eat their Kazakusan.
You will lose 9/10 times against quest hunter. The only times i've beaten quest Hunter with this deck have been when i have managed to use Zola the Gorgon on Reno Jackson and also drawn and played Spice Bread Baker and Alexstrasza the Life-Binder to heal up.
With mulligans always keep Reno Jackson and when playing agaisnt aggro decks keep all the low cost anti-aggro spells. When playing against Demon Hunter or Paladin keep Rustrot Viper because of Dreadprison Glaive and The Immovable Object. Also Queen Azshara is always nice to keep in your starting hand.
I am going attempt to use this deck to push from Diamond 5 to Legendary. This will be extremely difficult as in the current meta as the only decks you can really get legend with are the tier 1 decks everyone else will be using (none of which are Warlock).