Let's say Mage is the only class you have at level 20. There are 9 basic Mage spells. So you need 12 7+ cost minions. Stormwind Champion, Core Hound and War Golem are the only basic 7+ cost minions. Even if you have a few extra spells, you might not be able to complete a deck.
My first thought was mage. A ton of removal, Double mirror entity, effigy, counterspell even ice barrier and ice block aren't bad just to get some value out of the first 6 turns. Then play some big stuff and alex/burst him down. I had the rhonin/Tony combo as well as frost nova to stall/protect the board/make fireballs.
Don't think it's the best deck out there for this arena but it worked OK.
Made a astral communion druid deck that was pretty fun in this format.
Took my first ass whooping at the hands of one of these. He played Astral, discarded two garbage cards, then he immediately top decked two consecutive Nourishes and proceeded to own me.
Astral Communion and ~17 fatties seemed like a no brainer. But every time I would power one out early, I would topdeck stuff like Swipe / Rend / Wraith / etc.
I just did aggro shaman without the low cost minions but with powermace, axe, bloodlust (usually hero power a lot early on), and some big bodies. As long as you can draw a doomhammer its pretty much gg
I absolutely destroyed every game with 28 spells + 2 eaglehorn bows. I didn't even run quick shot or KC. Just gotta make people misdirect fatties into their own face and spam your HP.
Won my second game with this gem of a deck on my f2p NA account. Those were all my eligible minions and all but 3 of my spells. The other guy was trying to play a legit deck as well.
tried to upload the second image but tinypics captcha is driving me mad
there is 2 frost elemtals, one of the 5/6 heal for 6 dudes and a jormungar or what ever its called