Hearthpwn

Tested this custom made deck since I am a long-time fan of C'Thun Rogue. My favorite card is Blade of C'Thun.

Recommendations: I do not have Twin Emperor Vek'lor but I highly recommend running that card as it provides an 8/12 body for only 7 mana as long as your C'Thun is 10/10. Harrison Jones works for card draw but if you want life, replace Harrison with Gluttonous Ooze. 

Brann Bronzebeard provides devastating combos such as a double stat buff on a huge minion with Blade of C'Thun, Lab Recruiting shuffles 6 copies of a minion that you think you'll need more later on, which also increases the chances of drawing that minion in the next few turns. Comboing Brann with C'Thun almost guarantees lethal, or worse case scenario threatens lethal. 

Lab Recruiter is a strong card that enables flexibility to choose what you think will be more useful later on to shuffle into your deck. Example: You can shuffle Zilliax against aggro, Blade of C'Thun/C'Thun (with Shadowstep) for more threats to destroy later on. 

Tomb Pillager might be an odd choice to add but a 4 mana 5/4 with a coin after it dies has helped me pull out Blade of C'Thun one turn early in crucial moments. Also forces the opponent to deal with something on turn 4 while allow me to use my Combo cards in case I go first against opponents. 

Mulligan: Mainly keep Backstab, Fan of Knives, Elven Minstrel, Eviserate, Tomb Pillager, Zilliax (against Aggro/Even Warlock). Also, any card draw you have in your mulligan should be kept as you need your minions more when you start using Blade of C'Thun combo with Shadowstep or Sonya Shadowdancer, etc. 

Win condition: Tempo on board or C'Thun. Usually the only way you lose with this deck is if you do not have enough card draw or resources late in the game. I've only lost one round so far because I missed Elvin Minstrel.