Hearthpwn

You could try putting in a Body Wrapper. - If you actually draw Malygos, you can just play it - if it sticks, you can burst the opponent down. If it does not stick - you can reshuffle and complete 4/10 of the quest at the same time.

As I think of it now - this would mean sticking to the original plan of Treant generators instead of Crystalsong Portals like @YellowPato suggested - the discover option treats treants as one, so it won't mess Body Wrapper's second combo chance when discovering. You should also get rid of other non-treant-minion-generating cards, so the Discovery pool has 3 creeps at max.

Duuuude, this seems kind of funny. At first I had a really dumb moment bc I forgot that the quest needs to spends mana ON MINIONS and no on spells/cards. And I thought that I missplay the card xD.

But, now I'm really trying to play this OTK and thinking in ways to improve it.

For example, adding Crystalsong Portal x2, bc unless u had some of the Treants that Witchwood Apple adds to your hand, u always will get 3 random minions to complete the quest faster and have better board control.

Secondly, I think adding a second Strength in Numbers makes it more reliable bc only having one in the deck doesn't seems convenient. If u don't have it in your opening hand each turn the chances of drawing Malygos and not being able to do the combo is increased.

And finally, I'll suggest trying to replace 1 Ferocious Howl and 1 Dreamway Guardians with 2 Savage Roar . Or at least just the 1 Ferocious Howl if you want to keep the 2 mana minion generator. Bc with the amount of Treants that u generate, u could maybe find a finisher turn with 1 or 2 Savage Roar . And in that way u have a 2nd opportunity to win if ur OTK Combo fails somehow.

Here I is and idea deck of what I was saying https://www.hearthpwn.com/decks/1326093-sidequest-free-malygos-otk

the idea is cool, if you draw Malygos at least you have 12 face damage on turn 9 with 2x Moonfire

This is the most stupid deck I ever saw. What if you draw the MaIy? and what is you do not draw the Witchwood Apple. The fact you need to have MaIy in your deck and two swipe and two moonshard in hand is stupid

It's not stupid: it's challenging. No one ever said this deck is competitive, and if anyone thought that it's clearly that he's not a reasonable person.

To be honest, calling this deck stupid makes you so, cause you're not able to understand that the OTK is not reliable at all and that's why it's so cool when you finally pull it off.