just answering the latest posts.
all casual means is that it's not ranked... there is no leaderboards or nothing else besides "fun" factor... if it were to balance out the decks... it would need analyze your entire deck... plus the ai doesn't know whether you know how to play your deck or not... all kinds of equations would have to be done which would make your queue timer last more than 20 minutes or something to find a match. what would be the fun in always facing equal opponents? you would have a 50% win percentage... don't you want to get some crappy opponents so you can finish your dailies faster?
as for where to find decks, i already stated this... hearthpwn.com, tempostorm.com, hearthhead.com ... hearthstoneplayers is a lame site... not sure why some of you are glued to it. no one goes there but you guys on this forum. lol. hearthpwn is the most popular site... its owned by curse... curse is semi official to blizzard... all the info about blizzard games gets released on curse sites first... for wow its mmo-champion.com, for d3 its diablofans.com, for overwatch its overpwn.com, for heroes of the storm its heroesnexus.com. hearthhead is from zam networks or whatever they call themselves, they are the second most popular sites when it comes to blizzard... zam owns wowhead.com which is the #1 destination in wow for questing, achievements etc... and tempostorm is one of the leading professional hearthstone teams in the world, they allow people to post decks and the team posts the ones they've used in tournaments or ranked play.
anyways... when you open packs, the cards will not automatically be cards you don't have... otherwise blizzard would not make any money. and this is how it has worked for all collectible/trading card games. if any of you ever played magic the gathering... you could buy 20 booster packs and get no new cards. the system in hearthstone is completely random, but the good side of hearthstone is that the cards you already have can be turned into dust... dust is what you use to craft new cards or golden/foil cards.
the reason i tell you guys to not spend your gold on packs is because when you will eventually get better at arena, the rewards will trump the 100 gold per pack limit... because if you get 12 wins in arena... you can get up to 500 gold + pack + golden card + dust... you only need 4 wins to get your 150 gold's worth that you spent... this comes in a pack, gold and dust.
here's my winnings... i'm only posting them to prove that i know what i'm talking about, by no means am i bragging... a twitch streamer named kripp has over 9000 wins. most of them in arena. i'm defending this game for some reason but i really dislike it because its cards... i don't feel like i have the control over whether i win or not... which is why i just do my dailies and get it over with.