I went 16 - 8 with this deck. I played in legend from rank 11.000 to 5.000. The deck is great against most kind of slow decks, mainly the Druid decks and the slow Hunter decks. It might struggle against the aggressive decks. Luckily, i played against few of them. I played most against Druid and Hunter and there the deck has shined. Also the deck is fun to play. So i think this deck is a great choice, if you expect a field with few aggro decks.
First of all, thanks for the upvotes. I played the deck further and my record is now 26 - 11 with a win rate of 70%.
In the core this deck is a Hadronox deck, i.e. you try to build massive board states with taunts in the late game, that your opponent can´t handle. Instead of using Witching Hour, it uses Barnabus the Stomper to combo Cube and Hadronox in the same turn. This way, you can play Malfurion the Pestilent and Spreading Plague and it is less weak against things like Polymorph that give you beasts or transform/ silence your minions. Also, this way you can be a bit more proactive, since Barnabus the Stomper is a good tempo play on its own.
Against slow decks yoor plan is to complete the Quest as soon as possible. The 5 attack minions help to pressure the opponent and once Barnabus is played you can start making huge tempo playes by making big boards out of nowthere. The key here is to combo the Hadronox with the Carnivorous Cube. This should win you the most matchups on its own, so you don´t have to hurry, because you win the late game nearly every time. Often you don´t even need this, since you can buil big board states with many big zero mana minions.
Aggro matchups can be tough, because you don´t have many things in the early game and not so much early taunts like other Druid decks. Here the Quest isn´t so important and the plan is to use the good defensive druid cards. Malfurion is important and also Spreading Plague. The 5 attack minions might help to get board presence if you have the time.
Always keep Wild Growth and Oaken Summons. Nourish and Cursed Disciple are also cards that i would keep most times. Lesser Jasper Spellstone i would keep except for Druid and Warrior. With the rise of token Druid maybe also against Druid. Steel Rager maybe againt Warlock and Rogue. Spreading Plague against Paladin. I would consider Harrison Jones against Rogue and maybe Naturalize against Warlock for Mountain Giant. I considered mulligan the Quest against aggresive decks and it worked in part, but the problem is, that there are few classes there you are guaranteed to face a aggro deck and in the other cases you would win with the Quest more or less guaranteed. So i´m not sure if this is correct. Maybe against Paladin.
This is the first version i build and since it worked so far, i havn´t changed it. I think it is not optimal yet. Maybe some more early cards would be nice, to help against the aggro decks. I´m not sure if two Steel Rager are necessary, since most times you are able to fulfill the Quest quite early anyway. There are also few big taunt minions and sometimes you have Hadronox and Carnivorous Cube but few things to get back. But most times this doesn´t matter that much as mentioned above. Maybe some Primordial Drake would be good or Witchwood Grizzly. By the way Damaged Stegotron is a great addition to the deck, since it triggers the Quest and is really good to bring back. I think the recruit package is great for the deck especially with Steel Rager. However Steel Rager is situational and sometimes does nothing. Harrison Jones is also great, because it helps against Skull of the Man'ari or Twig of the World Tree and can be an additional card draw, which is also important to the deck. In the worst case it is a 5 attack minion that triggers your Quest.
Plays to watch out for:
If you played already the Barnabus, Oaken Summons can put out every minion in your deck. This can be great for getting The Lich King and Damaged Stegotron, but be aware of that it can pull out Cube and maybe ruin your Combo.
The great thing about this deck is, that it sufficces to having one of the two Cubes or Hadronox in your deck, while playing Barnabus, to pull of the combo. I havn´t lost a game because of drawing all three pieces before playing Barnabus (at least i think so).
If you can afford it, it is worth to play Ultimate Infestation after you played Barnabus, because then you can cast some minions you have drawn in the same turn for a big tempo swing. This decklist has not so much minions, so it can happen, that there are no or few minions that you have drawn. But against slow decks that should not be a big problem.
Against some decks it might be worth to consider not to summon taunts with Malfurion the Pestilent or not to play Spreading Plague, because you don´t want to get back small taunt minions with Hadronox.
Like in all other Druid decks Branching Paths is an important card and it helps to close out games if you managed to build a big board, which is the main goal of the deck. Also it helps to stay alive and get you to the late game there you are heavily favored most times or to draw into your zero cost minions.
I have not mentioned it before, but the deck is quite expensive, since it has many legendaries and epics. I think some can be easily replaced. King Mukla and Harrison Jones aren´t that necessary to the deck and you can replace them without much care. The deck misses some of the good defensive Druid cards anyway, like Swipe or Wrath, so that could be good options. Giggling Inventor should also be a good choice. However, I´m not sure if you have enough 5 or more attack minions in this case. A second Guild Recruiter is also worth consideration. Some other 5 attack minions, i considered, are Fatespinner and Ancient of Lore, but i´m not sure if they are good enough. The other legendaries are more or less essential to the deck so i would not recommend to replace them. The epics are all quite important. Maybe you can cut one Ultimate Infestation or some Branching Paths.