Happy New Year! Starting 2019 with the

Treant

Introduction
The Ent was one of the first D&D Creatures introduced in the "White Box Set" in 1974. For copyright reasons the name was changed to Treant, but it stayed the same: a humanoid tree protecting the forest.

Art
The art is okay, I like that there are still leaves and mushrooms growing out of the Treant. The face looks a bit like a drunkard, which is not bad for the fluff per se, but in my opinion the face is too human without good purpose (see in the fluff section). Odd thing is that it seems to have four arms, but the description talks about "its arms" and I kinda like the idea of it having multiple arms and legs, so: why not :)

Purpose and Tactics
The Treant is straight forward: Good Armor and Hitpoints combined with a solid physical resistance, which is not even bypassed by magical bludgeoning/piercing attacks. It has a good chance to hit and does quite some damage, though its reach of 5ft. is pathetic, expecially for a huge Creature. The ranged option is strong, though its a up to the DM if there are any rocks around to throw. The rocks combined with the siege monster trait make them very good against structures, as 8d10+12 is huge damage. They are weak against fire as usual, which still makes makes no sense at all. All in all the Treant is a solid Brute.

Two things make it stand out and justify CR9:

1) The Treant is an excellent ambush fighter. Even as it has no skills, the False Appearance should enable it to a surprise round.

2) The Treant can animate up to 2 trees which have the same stats as the Treant. In my opinion this is a great tool for the DM as she can decide on the spot if there are one, two or three Trees fighting against/by the side of the heroes

So a Treant can stay camoflaged as a Tree, then use its suprise round to awaken two trees thus encircling its opponents and have the awakened trees keep them busy in melee while pelting them with rocks.
Aside from combat they can fill basically every role you need them to: They can be quest-givers, unexpected antagonists, allied forces of the heroes, can provide rare knowledge or could be even used as a material component in something sinister.

Fluff
The fluff section is Ent/Treant 101:
Some Trees have the potential to turn into a guardian of the forest and transform into a more or less anthropomorphic Treant. Those have some powers over nature (animating other trees and control over some animals), but the text is ambiguous if every Treant possesses them. They are chaotic good and won't go after people respecting the forest, but will attack those who try to destroy the forest. So basically its the classic Ent/Treant from Middle Earth and every other Fantasy World featuring similar creatures.

Spoiler: Thoughts on Treant Physiology
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I get that its not necessary to explain everything in a magic world, but I would be curious about their biology: The picture shows a humanoid face, complete with eyes, eyebrows, cheeks, nose, mouth and something like a chin - in the text they are called "face-like features". But what does it do with those? I guess the mouth is for talking and the eyes for seeing, the nose for smelling, but should a Treant really need to grow a nose to be able to smell? Does it have to eat with its new mouth and if so: what does it eat? Meat? Plants? If you poke it in the eye will it go blind? I know that the Treant is a classic and the anthropomorphic features don't bother me. But I always like those more alien creatures and I think the Treant should be one of them.


Hooks
A group of dwarves have a camp in an old forest and are producing charcoal, as the old, somewhat magic Trees make the perfect coal for smithing. Recently some of the woodcutters got lost in the woods and the dwarves will pay handsomely if someone could ensure their safety.

Treants can grow very very old, but even they have to die at some point. Oaksplint the great knows that his time will come soon and is worried about the protection of his forest. He senses that a new Treant will emerge soon, but the new guardian is not fully awoken yet and he knows that a group of mercenaries is roaming the woods in search for the young Treant to fell it and sell its priced materials to reckless alchemists.

A wood elf bard is in need of assitance: He wants to discover old elven songs from a long extinct tribe of wood elves. He knows that in their former forest lives an elder Treant and he is sure that he could help him with his knowledge. The problem is to find said Treant and get him to talk, as he was not seen in years and he suspects the Treant to be sleeping.

Verdict
I did not check, but I am very confident that every Monster Manual through the editions featured a Treant and it is right to do so: They are a fantasy staple and all in all solid creatures which do not disappoint.