Hearthpwn

I'll consider adding a detailed write up to the deck if it gains some popularity. 

Basic Mulligan:

Looking for Undertaker + Mad Scientist as initial hand for best undertaker value. Loot Hoarder is another good one to combo with here.

Frostbolt is a good card to keep for early minion removal.

Keep Water Elemental if going second.

Basic Gameplay:

The goal of this deck is to control the board in the early game and deal damage, then finish the game with spells and minions. Frostbolt is mainly used for board control, so don't feel shy about using them to take out early undertakers or wiping Harvest Golems out on turn 4+ with hero power. As the game continues, the Water Elemental helps make good trades on the board, or can freeze heroes with weapons to stall their attacks.

You'll want to hang on to Archmage Antonidus until you can combo him with a spell, since most players will aggressively try to remove him on their turn. I've found playing him with either Duplicate or Counterspell has proven to have the best results, since it either keeps him on the board or gives you two more for them to deal with.

If all else fails, Ragnaros the Firelord and Pyroblast will finish the game for you.