Hearthpwn

Basically the point of this deck is to assemble Exodia by copying a Sorcerer's Apprentice twice with Simulacrum and then reducing their cost to 0 with Leyline Manipulator. Once you have that, you need Antonidas, your natural Sorcerer's Apprentice, the two 0-cost ones and a Molten Reflection and you have assembled Exodia giving yourself infinite 0-cost Fireballs.  

Generally this deck plays extremely defensively and in the early to mid game you have 3 objectives - deal with the enemy's pressure, cycle through your deck and don't mill yourself. 

The skill cap tends to be quite high and it can be a very difficult deck to learn due to its unorthodox playstyle and constant battle between the 3 main objectives listed above, but that also makes it a very rewarding deck to play well and win with.

Hand size is a very big problem with the deck as there are quite a few cards you have to hold on to (the combo) as well as some cards you generally want to hold on to until you can use them for good value (Nova-Doomsayer, Blizzard, Flamestrike). You have to be very careful when playing your Acolytes that your opponent doesn't end up milling you because if you lose your combo you lose the game. To help with this issue I run 2x Frostbolt and 1x Ice Barrier to have a few more cards to dump and clear hand space, as well as to help against aggressive decks, though they can be replaced by other choices like Polymorph or Gluttonous Ooze.  

Generally your bad matchups will be aggressive decks (Hunter, Odd Rogue, Odd Mage) though they are still very winnable due to the strength of the Mage control package. A very bad matchup are faster OTK decks (most notably Maly Rogue, but also Maly Priest to a degree) as you are usually quite slow to assemble your OTK and have no way to counter theirs (you could tech in Counterspell if this is a huge issue in your meta but it doesn't help much).  

Good matchups are all decks that don't pressure hard or threaten to OTK you quickly - Druid (just watch out for Naturalize milling your win condition - dump cards if you have to), Control Warlock (99% of the time the only way they can win is Demonic Project so try to hold as many minions as long as you can to help your odds of surviving it), Mecha-Thun decks, Warriors, Paladins and Priests. One notable matchup is Shudderwock Shaman where you are extremely favored and can only lose if your opponent assembles their combo extremely quickly AND yours is at the bottom of your deck or you get very unlucky and can't deal with their minions.  

Overall I think this is a very viable deck even for ladder as its worst matchup by far (Odd Rogue) has fallen off in popularity extremely hard, it's second worst matchup (Maly Rogue) is very rarely played, and its other bad matchups (Hunter and Odd Mage) are not all that unfavored and can be further improved with some tech choices. In the right tournament meta this deck can be an extremely reliable monster.