Between rank 5 - 4:
Im having a lot of fun with this deck lately, and after a lot of tweeking, i think i finally found the best version for a Mecha'thun deck in this current meta, and i thought i should share before it goes out of rotation in 2 months.
Just like the Spanish Inquisition, nobody expects the Mecha'thun at the end due to the mech package in this deck, so no one bats an eye when they see the Galvanizers being played. A lot of times when i get to the end of the deck and the enemy is still healthy, they get cocky and begin to emote BM, just to get obliterated by a sudden Mecha'thun 2 turns later. lol
If people like the deck i can make a little write up later.
Update 1 - Since i made this post i played some more games with the deck, not as many as i should, i know and here's my current stats with it. Of course i didnt expect to maintain the WR above 80%, and after 31 games, i stabilized around 70%~ at rank 3, which i think is still fair for any competitive deck. Will update the title, for transparency sake.
So far, as you guys can see above, my hardest match up is rogue, which isnt thaat bad, i can still win sometimes if they don't get half their deck discounted to 0. lol
And against the aggro-y decks, like Hunter, Mech Pally and Galak Warrior, i have the upper hand. A breeze agaisnt the pure control ones, like Ress Priest and Control Warrior.
Hunter / Mech Pally > Dark Skies or Plague of Flames, Mortal Coil, Hot Air Balloon, Mecharoo, Galvanizer, Upgradeable Framebot, Zilliax. keep Sacrificial Pact against Hunters (very tasty against Frenzied Felwing).
Galakrond Warrior > This one is kinda like Galakrond Rogue, in the sense that they wont win by either rushing your face early or fatiguing you, but bursting you mid game with their Galakronds, so you should try to be in a good spot hand-wise to be able to respond when they begin to unleash their buffed/discounted cards.
Thats why i always keep Valdris Felgorge or a Veiled Worshipper, Dragonblight Cultist, Devoted Maniac, Plague of Flames (to deny Acolyte of Pain, Bomb Wrangler, Eternium Rover, ).
Rogue / Shaman / Mage > Valdris Felgorge / Veiled Worshipper, Dark Skies/Plague of Flames (Plague for Rogue and Mage to prevent early Edwyn or Giant xenanigans) , Mortal Coil, Galvanizer, Mecharoo, Hot Air Balloon, Upgradeable Framebot, Dragonblight Cultist.
Priest > Valdris Felgorge/ Veiled Worshipper, Dragonblight Cultist, Devoted Maniac, SN1P-SN4P, Dark Skies .
Against Hunter, Mech pally and Galak Warrior:
Forget Mecha'thun. You won't win against any aggro deck by playing the combo, so push face damage whenever possible. In resume: play like you're an aggro deck, flood the board, trade efficiently, hit face. No need to save Grim Rally, use it offensively. If you have to choose to play the invoke minions or the mechs, gor for the invoke, Galakrond is your friend and can win you the game just by playing it.
Against control decks:
Sneak-in a hero power whenever possible, but be mindful that you'll ever only need to draw 20 cards, cause between Valdris and the Worshippers, you will HAVE to draw 10 cards no matter what, so for example, if you have 10 cards left on your deck and you didn't draw Valdris Felgorge yet, be carefull with fatigue damage, cause sometimes it can it screw up your games when 2 of these 3 cards are in the bottom of the deck.
Also, remember that sooner or later you will have to pay the mana cost for every single card in the deck in order to win with the Mecha'thun combo, so try to not have too much mana laying around when possible, cause it could mean that you can cast the combo 1 turn early.
Don't you dare hit quest priest in the face. ever. Mecha'thun is your friend. Play only for the board, and seek for a removal before turn 09, when they'll possibly play Zerek's Cloning Gallery or Mass Resurrection. Don't over commit fooding with your cheap minions. Remember you need hand size for a Dark Skies and cannon fodder for Plague of Flames when they play Mass Resurrection.
Hope this help someone struggling with the deck. I'll try to answer any question in the comments.
Have a nice day! o/