Hearthpwn

Muligan

Vs Warlock , Shaman and mage:

we want early mana bust . We want on early hand Wild Growth , Greedy Sprite Nourish 

we can save Naturalize vs Mountain Giant  vs warlock

Vs agrro there are Paladin , Hunter , maybe Rough :

We want on that mutchups table control Spreading Plague cope with it very well , another card can controled table too there is Primordial Drake

you want armor too in that mutchup there is Branching Paths   Ferocious Howl and Earthen Scales 

Vs War , Priest and Druid : 

it's very long matches, you can save both mana boost and control, because during the match the cards in the deck will reach the end

 About the replacement , I would not recommend anything to change but you can replace : Branching Paths -> Ultimate Infestation

Good luck and Have fun