Hearthpwn

Update: Used the same deck in Season 2, but removed 1x Shattered Sun Cleric and added 1x Hellfire. 

I used this deck to go from Rank 3 to Legend in the first official season. It's been doing well for me in Legend, staying in top 100 at least.

The majority of cards provide some instant benefit the turn they are played, so you want to mulligan away from those cards and if at all possible, make the maximum possible use of their instant effects.

There's a lot of standard cards here, for a Zoo without Doomguards. I'll try to explain the variances:

• 1x Hellfire
  I actually didn't put it in here as a response to the mirror, rather, I went through a series of Hand Lock and Ramp Druid matches that I lost because I couldn't get past the taunts to deal an extra 1 or 2 damage. Hellfire is at the very minimum an extra 3 damage and if played late game, can clear out a taunt to let your chargers get through. Power Overwhelming on a minion that would've died to Hellfire is also a great combo for some extra damage.
• 0x Shieldbearer
  I would want to be running more persistent buff cards. This deck focuses on dealing enough damage while controlling the board to get your opponent to lethal range for your big combo.
• 0x Flame Imp
  I found the damage I took from them to be not worth the cost in the long run. This deck is not as top deck rushy as the Doomguard version.

Edit: Dropped 1x Arcane Golem for 1x Ironbeak Owl. I got bored of zoo for a bit and messed around with other decks. Tanked myself down to 1000+ legend. This deck brought me back to top 50 in a day.