Big Control Warrior

[Decklist Update #1 (Day 2 of Wailing Caverns): Replaced 2x Sword and Board, 2x Execute, C'Thun, the Shattered, and Yogg-Saron, Master of Fate with 2x Stage Dive, Bulwark of Azzinoth, 2x Barricade, and Kresh, Lord of Turtling. Apparently when you replace mediocre, situational cards with better, more flexible cards, the deck's winrate goes up. I'll update the guide below later as able.]

Intro: The goal of this deck is to remove all your opponent's threats for 6-7 turns, then turn to your Big Warrior gameplan to flip the board in the late midgame. Like all my decks, I'm posting this because it's super fun (at least, I enjoy it!) and it's been good in a small sample size (5-1 at D5 and D4). Obviously that's no guarantee of universal success or future success, and the good record could be due to either variance or a favorable pocket meta, but it's felt quite strong so far!

Matchups: In theory, this deck reliably beats Demon Hunter, Mage, Libram Paladin, Priest, Rogue, and Warrior; has a decent chance of beating Hunter, Shaman, and Warlock; has to rely on good draws vs. Druid; and has a horrible matchup against Aggro Paladin (unless it's a list running Ogremancer).

• Demon Hunters get melted by our deck.
• The two Druid matchups depend pretty much entirely on whether you draw all six of your AOEs.
• The Hunter matchup depends on whether you draw both Rancors. If you do, and if you can prevent the Hunter's 5-attack minions from connecting face, you win. If you don't, and if you can't, you lose.
• Rogue is incredibly susceptible to Rancor; the key is stacking armor past the Alexstrasza/Tenwu of the Red Smoke combo breakpoint.
• The Enhancement Shaman matchup depends on whether you're able to put taunts in their way early enough--Bru'kan is a brutal finisher, so it's important to keep your health as high as possible, since the taunts are wholly ineffective against damage over the top. Elemental Shaman depends on whether you can keep the midrange minions from punching you in the mouth.
• The Mage matchups are split: Spell Damage Mage is quite a difficult matchup in which you need to hope you can play a threat every turn from turn 7 onward (and that they don't have Counterspell or Mirror Image to counter any of those turns); however, Spell Mage and Ping Mage feel rather lopsided in our favor (two copies of Devolving Missiles aren't enough to beat seven big threats).
• Even though Nerubian Egg is statistically horrendous, it pretty much singlehandedly wins this matchup for Aggro Paladin. On the other hand, Libram Paladin doesn't run any sticky threats, so it gets eaten alive by our removal.
• In general, a Priest will only be able to deal with one of your two win conditions: (a) seven waves of very large mans, and (b) C'Thun. DO NOT, HOWEVER, UNDER ANY CIRCUMSTANCES PLAY Rattlegore. Soul Mirror, Psyche Split, AND Gift of Luminance WILL WRECK YOU.
• The Warlock matchup depends almost entirely on how quickly you're able to play Rattlegore, whether they're running Envoy Rustwix, and whether they play Lord Jaraxxus on turn 9.
• Rush Warrior is quite straightforward: remove their threats, and make sure to save specific removal for the buff cards and big stuff. On the odd chance you meet a Control Warrior, you'll win thanks to the wonderful science of probability: if one deck has C'Thun, and the other has C'Thun plus a quicker win condition, then...

Flex Cards: You could swap out Kargath Bladefist and Yogg-Saron, Master of Fate for Barricades (Yogg and non-Prime Kargath do have anti-synergy with Commencement); I chose to keep them because the likelihood of pulling one or the other is low--Kargath is a card you often keep in the mulligan anyway--and they're extremely helpful in a variety of situations. You could also swap out Sword and Board for Slam, but I think the former's one-mana cost synergizes better with Execute, and the armor gain has felt more valuable than the card draw.

Miscellaneous Advice: I've already touched on the first of these, but here are a couple combos to keep in mind: Sword and Board + Execute, and Rancor + an opposing Ogremancer (try to play a bunch of spells, then finish off with Rancor!). Rancor + Execute also reduces Jandice Barov from a big threat into a net loss of 4 health for the Rogue/Mage. Against a Mage, Mirror Image is probably the scariest secret, and your misplaying against it is one of the few paths the Mage has to victory; fortunately for you, you're almost always the control deck in this matchup, so just bide your time until you're able to play a Runaway Blackwing against an empty Mage board. Make sure to save some cheap spells to test for Counterspell the turn before you play Commencement, too, and if possible, bait out all the Mage's Devolving Missiles before playing Rattlegore (though if the Mage still has a copy and you have a chance to play Commencement, but Rattlegore is still in your deck, don't get greedy--Mages can't heal, so a 6-drop is still a major threat).