Hearthpwn

Despite all the hate and contempt Warlocks receive these days, this is the deck that made me able to reach legend on April 2017. Meet Murlock-Beastlock, these 2 tribes already play well together - as Gentle Megasaur and Zoobot show, but with tech cards like Hungry Crab and Golakka Crawler against Pirates, Murlocadin you can get free win with deck as fast and explosive like this one, able to compete with Druid and Hunter in that respect. Against more control-oriented ones it just kills them due to their slow starts, but is well able to survive even few aoes with smartly placed buffs and rebuild with Finja, the Flying Star, Primalfin Lookout and The Curator.

Why Warlock, if you use only 1 class card? Well, Warlock's hero power is one of the most suitable for this kind of deck and Seadevil Stinger gives this deck explosiveness no other card can. You can play Finja on turn 4 with it, it helps you play cards you drew with hero power. And it can create game winning chains with itself, you can play Stinger into Stinger into Coldlight Seer and boost them for killing blows with Murloc Warleader or Gentle Megasaur next turn.

All in all, rogue deck for sure, people won't expect you playing this one. I reached legend with it from 4th rank in just one not really long afternoon. This deck is probably more less in it's final form, but according to meta, it's still subject to change, for example If you meet more Hunters and Taunt Warriors you might replace Crab or Crawler with Flame Imp.

Have fun!