I'll write a guide at 10 upvotes
As promised, the guide to play this gem of a deck!
Firstly you need to know how to pull off the combo:
Forest Warden Omu -> Germination on Forest Warden Omu -> Malygos -> Any 0-cost or 1-cost spell to refresh your mana crystals again -> Burst your opponent to 0 with Swipe and Moonfire combined with Solar Eclipse
The combo can become even nuttier when you are able to discount Malygos or Forest Warden Omu due to Jepetto Joybuzz. What happens here, is that you might be able to get multiple Malygos on the board for a combo that can deal way more damage.
Imagine you got a 1-cost Malygos from Jepetto Joybuzz, You could Forest Warden Omu -> 1-cost Malygos -> Solar Eclipse (which refreshes your manacrystals) -> Germination on Malygos to make 3 of them (Leaves you at 6 mana) -> Burst you opponent down to 0.
Then maybe the most important part of the deck: How to play towards the combo?
The most important thing is knowing is which matchup you are:
Shaman: Really hard. In general you need early removal + ramp. Shaman will take it slow until turn 5 to get that Boggspine Knuckles in play and just highroll the game from there. Mulligan: Lunar Eclipse, Wild Growth, Overgrowth, Guess the Weight, Nature Studies.
Warrior: Pretty Easy. You just want ramp and draw. As long as you don't do a lot in the early game, the Warrior won't either. So ramp up, draw your combo and maybe try to get a early Ysera, Unleashed in play. This will keep him busy during the game, so it will give you time to assemble your combo. Mulligan: Wild Growth, Overgrowth, Jepetto Joybuzz, Gadgetzan Auctioneer, Nature Studies.
Paladin: Kind of a 50/50 matchup. You need 1 or 2 early removals for minions that get buffed. As long as they don't highroll you with an early Libram of Hope, you should have the time to assemble your combo. Also if you know if he has little response to an early Malygos, you can just bump it on the board to gain board control and control the game from there. Mulligan: Lunar Eclipse, Wild Growth, Overgrowth, Guess the Weight, Nature Studies.
Demon Hunter: It's a tough matchup, but definitely winnable now with the nerfs. Soul Demon Hunter got way more popular than the Aggro version, which is good for us. He starts off somewhat slower which means we have the opportunity in the early game to ramp up. By the time he gets to his big threats, we can pop off with an Gadgetzan Auctioneer to burn through the deck and get the combo together. Mulligan: Wild Growth, Overgrowth, Lunar Eclipse, Guess the Weight, Nature Studies.
Priest: Almost a free win. The only thing Priest can do to disrupt your gameplan, is playing Mindrender Illucia. This means we have to get the combo as fast as we can. Mulligan: Wild Growth, Overgrowth, Jepetto Joybuzz, Guess the Weight, Nature Studies.
Mage: I haven't played a lot of mages, but in general they are Highlander if you face one. This kind of means they will play the control game, which is good for us. We just ramp up and burst him with the combo once it's assembled. Mulligan: Nature Studies, Wild Growth, Overgrowth, Jepetto Joybuzz, Gadgetzan Auctioneer.
Hunter: Since the nerfs i haven't seen a single hunter... The only hunter that was getting played was highlander, but the nerfs just killed the class. But if you do face one, i would try to get early removal and draw. The ramp isn't that important in this matchup, since the hunter will run out of steam pretty early if you are able to deal with it. Mulligan: Nature Studies, Lunar Eclipse, Guess the Weight, Lightning Bloom, Swipe.
Rogue: Apart from Shaman, this is a hard matchup. They can just highroll the sh*t out of you by getting an turn 3 12/12 Edwin van Cleef on board. If this doesn't happen, you have a 50/50 chance to win the game. Getting early ramp in is really important here. If you are able to get board control with your combo, do it! It often swings the game in your favor, and you'll be able to finish the game with Ysera, Unleashed. Mulligan: Nature Studies, Lunar Eclipse, Guess the Weight, Wild Growth, Overgrowth.
Warlock: This is a pretty easy matchup. All you need to think about is getting the combo into your hand, before they can burn your combo by using Tickatus. It's really easy to read if they will play it. You'll see weird plays on turn 7 like a no Soul Fragment Soulciologist Malicia. So just draw like crazy without overdrawing your combo. Mulligan: Nature Studies, Wild Growth, Overgrowth, Guess the Weight, Gadgetzan Auctioneer.
And if all this is still not enough, just pray to the Gods of RNG and slam down that Yogg-Saron, Master of Fate. It gets you out of tough situations a lot of the time by just eating the board, swing the board with 0-cost spells, you name it.
2) You could play Cenarion Ward in the deck, but it feels clucky to me a lot of the times. It sometimes stops your Gadgetzan Auctioneer drawtrain and can get in the way of your combo when you are overloaded and overdraw a combopiece this way. The synergy it has with Solar Eclipse is crazy good though, but for healing you could also just use Solar Eclipse with Crystal Power.
3) You could go for an extra Wild Growth or Breath of Dreams instead of a Wrath if you feel the meta if shifting a bit more to the controltype one. You'll get ramp more consistently, which makes it easier to run away with the game early.
That's it for me guys! I hope you'll enjoy the deck as much as I do!