To begin with: this deck is a total meme. You don't climb to legend with it.

With that said, the deck's idea is to increase the mana cost of your opponent's cards. This works the best against minion heavy decks, especially aggro or tempo ones. Against anything with spells or removal, you can put health buffs on Mana Wraiths and Nerub'ar Weblords, play Stonesplinter Trogg and hope they find it more threatening than the minions you want to keep alive, or you can play Lorewalker Cho and hope they don't want to give you spells.