That is so nice man. Id love Deathwing.
Use Boom!
I still play Hearthstone every week, but not as much as last year. I just do all the dailies while trying to climb the ladder with my druid deck. Got to rank 10 last month that way and 9 in March
I already had a Boom. That was my second one. So, now i have to hold onto it in case he ever gets nerfed and I can get full value for it.
It sucks though, now I can't quickly dust my rares/commons anymore. I have to manually do it.
How feasible is it to play this game and not spend any money now?
This game isn't P2W, it's more 'pay to have fun'. You can make cheap, winning decks ... but they usually end up being mindless aggro decks. When you get more cards, you get more options and can make more interesting decks.
I think the one thing you do 'need' to own is the Naxx adventure. There are too many strong cards in that set to pass it up.