Finally ran into someone playing that weird N'Zoth Shaman control deck. I was thankfully playing C'thun Warrior, and my build of CW does NOT lose to control decks. Guy was bad, which is fine, since it's probably not a deck he has a lot of practice with, but he got cocky late game when he was still at 30 health and used a healing wave on a minion to get a favorable trade.
I tried and tried and tried to get him to use his second Hex, but he wasn't biting. So I had to hold Emperor until I had C'thun and Doomcaller in hand, as both needed ticks (I managed to get two, which ended up being relevant). He had two somewhat damaged big minions on board (Baine Bloodhoof, Flamewreathed Faceless) and a totem, and I dropped my 8 mana C'thun (which was at 16) and just barely cleared his board while doing a little bit of face damage. Since he hadn't played Hex yet, I then shield slammed my own C'thun, killing it.
Why did I do that? His next turn was Sylvanas, Totem, Pass, and C'Thun couldn't be Hexed or stolen, which would have made my Doomcaller irrelevant. My next turn was Bran Bronzebeard, Doomcaller, and Disciple of C'thun on his Totem. This buffed my C'thun to 22 and put two additional copies into my deck.
He attacked into my Doomcaller with Sylvanas, stole my disciple (thank you two ticks of Emperor) and played N'Zoth, bringing back Chillmaw and one Cairne. (He wasted his Reincarnates on Earth Elementals which hurt his N'Zoth turn. One of the win conditions of NZoth Shaman is to use your Reincarnates on Cairne so at the end of the game you can bring back multiple Cairnes).
I then drew C'thun (the only two cards left to draw in my deck were C'thun, so not a surprising topdeck) and since Brann was still on my side of the board his 22 power battly cry was doubled. My C'thun cleared his board (except Baine) and did enough face damage to kill him.
I won that game because I shield slammed my own C'thun. There isn't a better "alpha" turn in the game than to play C'thun and then immediately kill it, and in match ups where you haven't baited out Sylvanas or Entomb or Hex or the like, it's also the correct play.