Having trouble getting that oh so sweet Heroic Naxx Card back? So was I! Until I found this deck. I was trying Taunts + Jades for ever But never got there until I found this. 

Credit goes to a Youtube user named Hogeco and I hope they don't mind me sharing this because it really worked for me after a couple tries.  

The idea is to barnes into Y'Shaarj - kill first stage and enter next stage with Vargoth and Sacrificial Pact x2 preferably. (I did it with 1)

Play Vargoth and Sac his demons and hit end turn. Vargoth will re-cast sac and hit him in the face killing him!

here is a link to the video:

https://www.youtube.com/watch?v=2hN_3ag1jmk