Hearthpwn

Good deck against most threats. Lot of heal and removals to win some time and cycle all deck. In this versin we have 2 ways to play our combo, to make us immune to Skulking Geist and make us more plastic to avoid Dirty Rat

Our main win condition:  Mecha'thun + Bloodbloom + Cataclysm  under Emperor Thaurissan (its not neccesary to make Cataclysm cheaper). 
Mecha'thun and Emperor Thaurissan-  is key cards of our combo.

Mulligan:

Try keep: Corpsetaker, Sense Demons, 1-st drops and removals depend on your expirience.

Never keep: buffers for Corpsetaker (like Cheaty Anklebiter , Annoy-o-Tron, Zilliax) and anyone from "Void party"

Advice:
1)Use DeckTracker to see which cards remains

2) If you milled Bloodbloom or Cataclysm - we have plan "B" by playing our combo with Plague of Flames , but its way harder, because we need play all cards before combo.

3)keep Defile + Acolyte of Pain  to make powerful removal+draw turn.

4)Bloodmage Thalnos  make some crazy combos with Dark Skies - deal 2 dmg to every hit, that makes 18 dmg to whole board max. Also stacks with good old Defile (2 1 1 dmg) .

5)To increase chances against Dirty Rat - just save Sense Demons for lust turn (that give 2 Worthless Imp to minimize pulling our Mecha'thun

Сonclusion:

Warlock Mecha'thun deck in last expension(for myself) was very strong, but in DoD Blizzard give us Dark Skies and Plague of Flames to make us easier to deal with fat threats like Mountain Giant, etc - that make our survival way better, like Bear Grylls :D

Its very interesting and fun deck for me, so enjoy an have fun! :)