Basically this is the deck I have been iterating on since I started playing Hearthstone a month ago. I have been able to reach Rank 15 with this deck.
The aim is to make favourable trades, slowly whittling down your opponent until you can finish them off with a combo such as double fireball on turn 8-9. The Pyroblast I included as in several games I needed that extra damage when I started losing control of the board in the late game. If you know that you are going to get outvalued, start looking for more face damage and some trades with your low attack minions.
Certain cards I upgraded or swapped out as I acquired them:
Most recently I made a more aggro variation (took out the Cobalt Scalebane and Bone Drake for more early game (Mirror Image, 2nd Sorcerer's Apprentice), which plays on ramping up the damage of the Mana Wyrms and Amani Berserkers.
Unfortunately the aggro version is reliant on a good mulligan.
I have very limited dust to be crafting new cards, so I guess this will do for now.
Any suggestions would be appreciated!
Update 18 Sep: I exchanged out the Chillwind Yeti for a Spellbreaker and it has made a difference in some games. The obvious use is to silence a taunt so you can get in more face damage, but one game I was able to unfreeze my Water Elemental to deal an extra 3 face damage for the win.