Hearthpwn

Mulligan guide: You always want Edwin VanCleef and 1x Preparation (but not 2x) in your starting hand. Just hard-mulligan for these 2 cards, and you'll be fine. Don't keep Preparation if you don't already have Edwin VanCleef in hand. 

If by Turn 2 (going second) or Turn 3 (going first) you still don't have Edwin VanCleef in your hand, it might be best to just concede and start over.

Play style: The goal of this deck is pretty obvious if you've played a fair bit of Rogue -- get a 10/10 or 12/12 Edwin VanCleef out on Turn 2 or 3 to give you a huge tempo. If the opponent leaves it unanswered, you've practically won the game. 

This combo is not unbeatable in this Tavern Brawl though. If your opponent included removal cards like Polymorph or Mulch in their deck, you're going to be way behind on card advantage, and will have to rely good draws with the eSportals to help you win -- but I'd just sooner concede and move on.

And even if they don't have a removal card, if your opponent gets really lucky with eSportal minions, you can still lose even with a 12/12 VanCleef. This deck may not give you a good overall winrate -- but that's not the point. The advantage here is that, win or lose, your games will go really, really fast.

If Edwin VanCleef decks start getting popular in this Tavern Brawl, it'd be a good idea to replace Shadow Strike with Sap.

Card choice explanations:

I only include 1 copy of Backstab because it's quite unlikely you'll have 2 targets for the card by turn 2 or 3. In some cases, your opponent may not even have played a minion (if the Summoning Portal gave them a high cost minion) -- so you use the Backstab to attack your own Target Dummy.

2 copies of Target Dummy simply because it's a 0-cost card, that can also prove annoying for your opponent to remove with their hero power/

1x Shadow Strike to remove a strong threat with Preparation in the starting turns -- or just as a means of removal in the later stages. In my most recent game, I had gotten my opponent down to 1 health, and was ready to end the game with my 12/12 VanCleef next turn. But then he dropped a 3/4 Fierce Monkey and a bunch of other minions that are bound to remove VanCleef if I don't kill him the next turn. Fortunately, I top-decked a Shadow Strike.