Hearthpwn

Very good in this meta, worst matchup is Galakrond Warlock but good against most other decks.

Deck doesn't just play itself, knowing when to time your weapon removal against certain classes is key. Plague of Madness can also go face at times. Of course can be used to diffuse many of the DH and Warrior weapons while at the same time comboed with Harrison Jones for hard removal + draw.

Chip damage and holding proactive minions such as Burrowing Scorpid and Southsea Deckhand is key.

In general, prioritize developing non-immediate threats before using your mana on instant impact (proactive) cards. While gauging if you can burst your opponent down from hand.

Against slower matchups: Get damage in while you can before Taunts come in. No problem using Cold Blood or Hooked Scimitar before the latter parts of the game (doesn't always have to be the killshot). Always play to your outs. Direct damage will clutch you many games.

Against faster matchups: Looking at you DH. Only trade against problematic (snowballing) minions. Don't bother trading unless it is a value trade with Skyvateer. I also have not been challenged by other Rogues and can say that this is favorable against the Secret/Lackey/Galakrond variants.

Mulligan

No Coin:

Spymistress Worgen Infiltrator Ashtongue Slayer

With Coin:

Greyheart Sage Frenzied Felwing

In general, throw away Backstab unless you are playing against DH/Hunter. Coin + Eviscerate + Felwing is also a viable play.

Exclusions

Flik Skyshiv is too slow. Most games with this deck should end on average turn 7.

SI:7 Agent was part of earlier versions of this deck but felt it was a weak link, since you couldn't always combo and was a liability against slower matchups. Felt bad to top-deck.

Shadowstep was tempting, but ultimately not proactive enough and often times difficult to find good situations to use it in. Also somewhat of a bad top-deck which this deck does rely on.

EVIL Miscreant again, not proactive. Does not pressure enough, more value oriented.