Hearthpwn

That's awesome! I'm glad the deck works for you. 

It seems like you answered your own question. You gave three issues that are preventing you from breaking out of your rank and the ways to go about solving them. I didn't answer your poll because you should be doing all of those things. I don't think there is a magic tip that somebody can give you that will instantly make you climb ranks. You just need to keep doing what you're doing and continue to be aware of things relating to your play-style that could use improvement. I'm a free-to-play player too, so I feel like the easiest way to improve is by controlling the one thing I have considerable control over: how I play. It takes a lot of time and resources to build a really great deck, and while I think you should definitely be working towards improving one deck, the one thing you can do now, that can have more or less instant results, is learn to play more efficiently and intelligently with the cards you have. I took a cheap Priest deck I made with only 2 rare cards and no epics or legendaries to rank 11, beating people with expensive meta decks. At some point, the increasing skill level of players prevented me from reliably outsmarting them with cheap decks, but the point is that you can do a surprising amount by manipulating your skill rather than your deck list. And skill isn't something that you need to buy. 

I'd probably do another 4-cost with high health. Priest of the Feast would be my choice, but since that's also from Karazhan and you might not have it, any other card that meets those parameters would be fine. 

Edit: Arcanosmith is actually from the first wing of Karazhan, so you wouldn't need to purchase the entire adventure to get him. It might be worth buying the first wing with gold. That way you can save the adventure for later (in case you want to complete it after it rotates out), and you'll also have Arcanosmith!

I realize I accidentally replied to my own post rather than to your subthread, but I suggested Acolyte of Pain above. 

I can't think of another card that fills the same defensive buff role for 3 mana, so you might consider an Acolyte of Pain. It's also three mana and it will give you some extra draw. Plus, it combos nicely with Power Word: Shield and Northshire Cleric.

Impressive what you have accomplished with so little dust cost. After some practice I've reached rank 13. Kudos! :-)

I...AM GLORIOUS! 

Love this shield.  Want this card to be at least in the meta just cause of his summoning text.