Why is Treant Protector banned?

He works very well with certain styles of play, while also being extremely strong in general.

Hero Itself

Treant Protector has extremely high base damage. With just a stout shield, he can bully an offlaner out of lane. No one can trade hits with him very effectively.

Skills

First off, his skill cap is fairly low. The main thing about him is to have good map awareness in early to mid game for effective usage of Living Armor.

Leech Seed

Most players pick this up at level 1. It is a huge slow that lasts something like 4.25 seconds, and is targetted.

An offlane that is caught by this will usually die unless they have a very good escape mechanism (e.g. Leap,  Power Cogs, etc.) This super slow, however, will often enable the other support to combo a spell of theirs.

While the hero is slowed, Treant Protector is free to attack them for about 80 damage a pop (prior to armor reductions). Considering a hero has between 400-600 HP to start, on average, that is a significant amount.

One popular way to utilize this is to have the other support buy most of the consumables so Treant Protector can begin with Boots of Speed. This allows him to quickly catch any offlaner and punish them with Leech Seed + Auto attacks.

On top of all these benefits, the spell acts like a Healing Over Time version of Mekansm.

Living Armor

The skill is frustrating to deal with. It is global range, so you can win other lanes with it.

The basic idea of the spell isn't to save allies, it is to allow for hyper aggression. You mid is able to dive, your offlane can really pressure their lane, etc. Mid is actually almost an automatic win, provided it is not heavily favored in the other direction or influenced much by ganks.

For teams like EG, this really gives Universe a lot of power in the offlane. Likewise, Arteezy can play aggressive and get kills, but it also is used to save him quite a bit because most teams will put lots of pressure on him, knowing he generally outlanes most pro mid players.

Additionally, when you have a few levels in the spell you can put Armor on a hero then have them wait ~10 seconds or so before doing anything aggressive. They use up the charges, and by the time the charges are down, Living Armor is off cooldown so they effectively get double the amount of charges.

Lastly, Living Armor can be used on buildings. This forces teams to commit to a push rather than slowly whittling a tower down. Split push becomes a lot less effective, as does using illusions to break base over time.

Nature's Guise

While strong, it is still a weak part of Treant Protector's kit. He can move around invis and cast without breaking invis, which is a benefit. However, mobility is limited by trees and it is more mana intensive than Treant Protector would like.

Overgrowth

Is particularly good at the moment.

It is considered a pretty good counter to Centaur Warrunner because it lasts a similar amount of time to Centaur Warrunner Stampede, has a similar cooldown, and prohibits movement.

Overgrowth also goes through Black King Bar, provided Black King Barhas already been activated on the target on the time of Overgrowth's usage. This helps lock down mobile, but squishy, Black King Bar carries like Luna(who is also popular in patch 6.81).

Misc

Blink Dagger

With the removal of mana cost from Blink Dagger, many STR Blink Dagger heroes became much more popular. Most STR heroes have mana issues, but this gives them huge initiation power, without being prohibited by their mana pools.

Treant Protector is no exception to this rule, and has benefited from Blink Dagger buffs greatly.

Weaknesses

Treant Protector does have weaknesses, but you can play around them.

• His mana pool is poor, so his spells are not initially spammable.
• He shines early game, and will slowly lose effectiveness (late game his best spells are Nature's Guise and Overgrowth)
• He cannot keep towers up if the other team commits to pushing one.
• Ticking damage will remove Living Armor charges quickly
• He really needs Arcane Boots + Blink Dagger to be very effective, but has no way of finding much farm (mostly relies on tower push gold and kills/assists)