A few suggestions, if I may.
Take Voodoo Doctor, Lord of The Arena and Darkscale Healer out.
Put 2 Blood Imps in.
You have a lot of 1 damage cards, which is not really going to help you in the long run.
Decide if you want to keep the Elven Archers or Argent Squires.
Mortal Coils are good for pinging enemies with shields, and as last hit, so you can draw an extra card.
You need Shadow Bolts.
Take Stormwind Knight out as well.
For 4 Mana it's just not worth it.
Try to get 2x demonfire if you can.
It's both a fantastic buff to your demons and a great damage source in a pinch.
Have at least 1x Shadowflame or Hellfire in your deck.
You need a bit of AOE just in case.
Alternatively, this seems very close to what you wanted to go for:http://us.battle.net/hearthstone/en/forum/topic/10785718466