I may not be actively playing Hearthstone, but for sure news of some decks dominating the ladder are music to my ears, as I'm ready to quickly theorycraft decks that could hit more than one bird with one stone. I've heard that Handbuff Paladin and Flamewaker Mage are the dominant forces of the meta, so here I'm with a... Mecha'thun Rogue?

...he's just our way to close out longer games. Your attention should be payed more towards the extremely, 2-Cost saturated curve that consists of mostly Secrets. They are cheap, disruptive, and enable Shadowjeweler Hanar to give us even more disruptive Secrets. But the real MVP that lets us actually hit two birds with one stone is Cloak of Shadows, and Evasion as an alternative. Because of Stealth or Immune, your hero can both evade a lot of targeted spells from Mages, and can buy a turn against Paladin.

About Mecha'thun, we use him to close out games if our disruption is not enough, which normally it will not be due to lack of burst. Simply play Galvanizer early on in the game before you go Preparation (or Foxy Fraud -> Backstab) -> Coerce on Mecha'thun. If you're luckier, your win condition may get cheaper through Efficient Octo-bot.

If you're feeling really frisky, you may consider playing Myra's Unstable Element or Field Contact to quickly get through one of three requirements for Mecha'thun to die - an empty deck. But we do have some card generation with Kazakus, Golem Shaper, so you may need to drop him beforehand. Actually, that may be what I need to do honestly, but he can sometimes save you out of sticky situations, so you decide.