This list carried me from Mythril 1 to champ in a 7 day, 70-34 blaze of glory during Beta Season II.
The deck was heavily inspired by RB Rainbow Rush decks of olde and Onieric's Beta Season II champion decklist, with a few notable changes. Allfather's Horn, Terpsichore Muse, and Mistwalker Gate give the deck a great deal of OTK ability and a little bit of mono B Valkyrie punch. Junkyard Valhalla is the other oddity when compared to classical Rainbow Rush lists and can give the deck some longevity against grindier decks and provide lasting value. Rush minions are great out of the yard and can be difficult to for your opponent deal with turn after turn.
This is a face deck all the way and you should try to avoid trading as much as possible through the early game. Mistwalker Gate can be key in situations where blockers are deployed in front of your first couple minions. Even a lowly Pup or Trapezist can smack for double digit damage with Horn + Giant's Stairway.