Just went from rank 3 to legend with this druid deck within the first week of the season on and continued to climb with it to top 250 legend on EU.
This deck is basicly good against most decks on ladder, because of the ability to build a big buffed board of minions to push a lot of damage as well as having Malygos burst as a late finish if needed.
Gameplay at Youtube - Bringing the deck to rank 75 legend (In this video I have added Twig for one chain gang)
In general its all about to push minion damage to face before malygos comes down in late game to finish them off, unless your minions haven't already done the job (which they normally do).
A common mistake is getting to greedy with the combo cards. Often the correct play is too play the combo cards out for tempo. After all, this deck is in many ways a tempo deck.
Against Baku warrior its all about pushing minion damage to face. Play the taunts and buff them with "Strongshell". If you manage that, you should be able to kill them with malygos combo when it hits. At this moment I am 6-1 against Baku Warrior in Legend, which is very high considering that this deck is in fact a malygos deck.
Well, the strategy against aggro is the same as always. Just don't die. Try to ramp in to plauge + tyrant, so you can play Strongshell the following turn. But this goes for most Druid decks.
I rally think its possible to add twig for one of the chain gangs, in particular if you want your Malygos combo to hit more consistent.
This deck might have some more fleksible cards, but I am struggling with finding other cards that can be replaced.
Some mulligan tips
Chain gang is always a keep with wild growth, no matter if you face aggro or not.
With cone, I think chain gang also is a keep since you can coin chain gang into Strongshell follow up and then push a lot of damage.
And as always, wild growth is always a keep.
In summary: Look for wild growt, chain gang and strongshell and of course spellstone if facing aggro.
Also "KiwiinBacon" has made a gameplay with the deck, in where he explains the deck over multiple matches. I recommend you to subscribe to his awesome channel. Here is the link to his video: