A bit late on this, hopefully you got it figured out
I was having the same issue, couldn't find a card or anything that stated spawning of said Treant, but I did find out that Symbiosis does spawn it but you have to play a nature card to trigger the spawn
Reflecting on the MM expansion I have to say I'm a little disappointed by the influence it's had on the game as I feel like it's been a rather small one overall. That's not to say the new cards aren't finding use, they definitely are-- and how.
But in terms of the flow of the game and strategies overal the concepts of old still pretty much reign supreme.
The exciting prospect that was 'devotion' has been overshadowed by the fact the strongest cards they printed were Oneiromancy and Ethereal. Of course SK had a ton of success with their devotion (as it was one of the more broken decks in HC) but the pay off has turned out otherwise underwhelming.
The archetypes they sought to support, Wild Hunt, Spies, Firesworn, are only really played as combo packages i.e nothing changed in that regard. I see the evolving cards played for their incredible point slam potential rather than their stage 3 archetype support. The echo cards (although I'm in favor of them) also have just made losing the coinflip ever more damning as playing your strong echo card R1 isn't a commitment anyway.
Playing the game now the highest tier lists are divided between spam engines and spam control and coinflip abuse is a clear noticeable factor in the way these lists are set up. It's very much a 'paper vs. scissors' meta where the deck you play is super favorable vs one deck and super unfavorable against the next. I feel that by turn 3 of any given game I can already tell whether or not I'll win and I've reached the point of boredom and frustration with it again.
As always I hope the next patch alleviates it a bit and given the leader changes it just might, but I should probably take a break until then.
But in terms of the flow of the game and strategies overal the concepts of old still pretty much reign supreme.
The exciting prospect that was 'devotion' has been overshadowed by the fact the strongest cards they printed were Oneiromancy and Ethereal. Of course SK had a ton of success with their devotion (as it was one of the more broken decks in HC) but the pay off has turned out otherwise underwhelming.
The archetypes they sought to support, Wild Hunt, Spies, Firesworn, are only really played as combo packages i.e nothing changed in that regard. I see the evolving cards played for their incredible point slam potential rather than their stage 3 archetype support. The echo cards (although I'm in favor of them) also have just made losing the coinflip ever more damning as playing your strong echo card R1 isn't a commitment anyway.
Playing the game now the highest tier lists are divided between spam engines and spam control and coinflip abuse is a clear noticeable factor in the way these lists are set up. It's very much a 'paper vs. scissors' meta where the deck you play is super favorable vs one deck and super unfavorable against the next. I feel that by turn 3 of any given game I can already tell whether or not I'll win and I've reached the point of boredom and frustration with it again.
As always I hope the next patch alleviates it a bit and given the leader changes it just might, but I should probably take a break until then.