Mecha'thun

Mecha'thun is a legendary neutral minion card, from The Boomsday Project set.

Strategy
Mecha'thun offers one of the few guaranteed win conditions in the game, but its requirements are very demanding. Not only is drawing out your entire deck a time-consuming process, emptying out your hand and clearing out all other friendly minions is just as tricky. Otherwise, as a vanilla 10/10 it's largely useless.

If you play Mecha'thun with no assistance, there is no guarantee it will survive to the next turn to combo it to meet the requirements. Even if you filled all the requirements, there's always a chance it could get silenced or transformed on the opponent's turn, negating all your hard work. One-turn combos are still possible however by summoning it through alternative means or using Galvanizers to reduce its cost to be more manageable.

Hemet, Jungle Hunter can delete your low-cost cards out of your deck to empty your deck as soon as possible. Keening Banshee also helps with deck thinning.

Potentials combos to instantly kill Mecha'thun include:
 * Druid:
 * Playing Mecha'thun followed by Innervate and Naturalize on Mecha'Thun will work if you have no other minions and cards in your hand. Alternatively, Dreampetal Florist can help reduce the cost of Mecha'Thun where you can play it + a Naturalize on the same turn.


 * Hunter:
 * Play Mecha'thun as well as two Ticking Abominations, using N'Zoth, the Corruptor and Feign Death (playing Emperor Thaurissan with these two cards in your hand will provide the discount you need) to resurrect them all and trigger all their deathrattles. This combo relies on only N'Zoth and Feign Death being in your hand, but ignores your board state as you will be dealing 20 damage to your own side of the board. Alternatively, using Galvanizer to reduce Mecha'thun's cost and having Goblin Prank as the only card left will ensure that Mecha'thun will die at the end of your turn.


 * Priest:
 * With no other cards except Mecha'thun, play Reckless Experimenter, Coffin Crasher, and 2 Ticking Abominations. Cards must be played in that order. This combo has the advantage of the combo pieces not being affected by Hemet.


 * Rogue:
 * Play an 8-mana Mecha'thun followed by Preparation and Walk the Plank. Rogues have the advantage of having Myra's Unstable Element to empty their deck once they drew the combo pieces. Anka, the Buried can also be used to make Mecha'thun's cost more manageable, as well as allowing use of other cards to kill Mecha'thun, such as Backstab or Shiv.
 * Reduce Mecha'thun to a 1 mana 1/1 with Anka, the Buried. Play Mecha'thun, then give it Rush with Serrated Tooth or Animated Broomstick. Cast Secret Passage with an empty deck then trade in your minions, making sure Mecha'thun is last. Since Secret Passage actually removes your hand from the game, Mecha'thun will trigger.


 * Warlock:
 * Play a Mecha'thun, followed by Bloodbloom and Cataclysm. This combo is the simplest to do, and can also be used with Genn Greymane strategies since all the cards in question (including the Galvanizers) are even-cost (the discounted hero power will allow you to draw through your deck more quickly as well). After the Bloodbloom nerf, it now requires extra mana discount effects. At minimum, it requires two Galvanizers and Emperor Thaurissan discounting both Bloodbloom and Mecha'thun. Alternatively, Drakkari Enchanter and Emperor Thaurissan can be used together to discount Mecha'thun and Cataclysm down to a 10 mana combo. Both Mecha'thun and Cataclysm have to be discounted all in the same turn. This requires an extra turn to set up in comparison to the Dollmaster Combo, but it requires less combo pieces and is less susceptible to counters like Dirty Rat.
 * Play Plot Twist while you have Dollmaster Dorian, Kael'thas Sunstrider, Mecha'thun, and any cheap spell (cost 3 or less) in hand. You can play the cheap spell before or after Plot Twist. Then, play Cataclysm. This version costs at least 8 mana to play and doesn't require mana discounts, and all three minions aren't destroyed by Hemet.


 * Warrior:
 * Play The Boomship with Mecha'thun and Malygos in your hand, then use Inner Rage on both minions and a Whirlwind to kill them both. This combo doesn't require Galvanizer, and you can have up to 5 minions on your side of the board provided none of them are above 6 health.
 * Play Mecha'thun at some point during the game (preferably after Dr. Boom, Mad Genius to use it as a 10/10 Rush). Finish with Da Undatakah, Inner Rage, and Devastate. This only requires four combo cards and three of the combo pieces have applicability in other matchups, although it limits you from using other Deathrattle minions.
 * A backup strategy with Mecha'thun Warrior is to use Galvanizer for a 9-mana Mecha'thun then kill it with Shield Slam. While there's no guarantee you will have 10 Armor, control Warrior decks often find themselves with very large amount of armor stockpiled up.

Lore
As the name suggests, Mecha'thun appears to be a mechanical version of the Old God C'Thun. This version of the Old God is unique to Hearthstone. It was created as part of Dr. Boom's Boomsday Project, "for some reason".

Trivia

 * A very early design for the card that became Mecha'thun was a doomsday scientist intent on destroying the world, with one version being a goblin called "Doctor Doomsday". Since its win condition was to destroy the whole world, it had to have a cost of 10 mana; specifically, a 10-mana 1/1 minion with the text: "Battlecry: If this is the only thing in your hand or deck or battlefield, you win". However, Blizzard then wanted to go one step further, requiring the player to have no minions in their battlefield in order to activate the card's effect, so it was changed to a Deathrattle. Having the minion be a 1/1 made it too easy to kill, and having a giant robotic Old God provided the cooler fantasy, so the minion was changed to the 10-mana 10/10 Mecha'thun.
 * Mecha'thun's flavor text is a reference to various famous C'Thun quotes from World of Warcraft, many of which were repurposed for C'Thun's original Hearthstone debut in Whispers of the Old Gods.
 * Mecha'thun's summoning quote reminds vaguely a quote from the Animatrix "Hand over your flesh, and a new world awaits you.", soon after that quote, there's a violent thermonuclear bombing explosion, resembling the dramatic deathrattle of this minion.

Patch changes

 * Added.