In a format that rewards spells that do a lot of damage, these enchantments can be game-winners.
In Magic: The Gathering, the color green stands for big creatures, faster mana, and brute strength. Commander is a format that encourages big, powerful spells, and enchantments are some of the most powerful ones. Green’s enchantments work nicely with the techniques it deploys. Some of the best enchantments can’t be used in other constructed formats for more than one reason.
Most of the time, a spell can’t be played in Standard or Modern because it costs too much mana. Commander, on the other hand, is a different animal altogether. Large spells are encouraged. Check your deck again to see if you can fit one of these in there.
Hardened Scales

Playing creatures that get counters is a common way for green players to win. With +1/+1 counters, you can make a creature with low power or toughness stronger. Many Simic decks, like evolve and adapt, have mechanics that add +1/+1 counters. With Hardened Scales, these creatures just get bigger.
With this one-mana enchantment, a Llanowar Elf can change from a 1/1 creature to a 6/6 monster. A few more spells would be needed for that example, but you get the idea.
Unnatural Growth

Green decks love to play with big creatures more than anything else. Think about making these huge things even bigger. Unnatural Growth does that, but it costs five mana. It costs a lot of mana, so it might be hard to play with a two- or three-color deck.
There are enough creatures that are all green, so this enchantment can be used in a deck. The great thing about Unnatural Growth is that it works in every phase of combat. Not only yours, but also your opponent’s.
Asceticism

Spot removal or bounce spells that target your creatures are the most annoying things that can happen in a game of Commander. Don’t you wish that every one of your creatures had hexproof? If you add Asceticism to your deck, it will no longer be hard for you to get rid of cards.
Even if the board is wiped, it won’t be a problem because Asceticism lets you bring back any creature as long as you have enough mana. Did your opponent cast Supreme Verdict? You can bring back your Vorinclex by paying one green and one regular mana.
Parallel Lives

With the right deck, tokens can get out of hand. They are even crazier in a deck with Parallel Lives, which makes almost twice as many tokens. Don’t forget that creature tokens aren’t the only kind of tokens. Tireless Tracker, what about it? You can’t forget about clue and treasure tokens, that’s for sure.
So, if you thought making creatures was going to get out of hand, just think about how much mana you’ll have with the right treasure token generators. If you add Bootleggers’ Stash to your deck, you’ll be able to play out your hand quickly. Anyone want a cute Swarm?
Guardian Project

In card games, you have to draw cards, and each color in MTG has its own way to do it. Green decks are good at playing creatures, so it makes sense for some parts of Slope Game to be tied to that. Green will be very strong if you give it an enchantment that lets it draw a card every time a new creature enters the battlefield.
Guardian Project is very useful in Commander, which is a singleton format. This enchantment only works if the creatures you play don’t have the same name as other creatures you’ve already played.
Sylvan Library

Sylvan Library is a mainstay of Vintage and could be one of the most powerful green enchantments in existence. It gives you some great card advantages and gives you control over the next card you draw. This is a powerful ability to have when you need to hide a card from Thoughtseize or when playing cards with Miracle.
For two mana, it’s hard to find an enchantment that gives as much value as Sylvan Library. In a format like Commander, paying four life isn’t a bad deal either, so you can draw new cards a few times before you have to watch your life total.
Garruk’s Uprising

It’s one thing to be able to draw cards, but it’s even better when a spell gives you more than one bonus. Garruk’s Uprising is more than just a way to get cards from your deck.. It gives trample to your creatures. Every creature on your side of the battlefield with trample makes it hard for your opponents to do anything.
It doesn’t seem like a big deal until all of your opponent’s creatures do damage because they’re bigger than their defense. For only three mana, that’s not a bad deal.
Growing Rites Of Itlimoc/Itlimoc, Cradle Of The Sun

When building a deck, it’s helpful to use cards that can do more than one thing. It saves room in your 100-card deck so you can add more spells. Because of this, the double-sided enchantments from Ixalan are great choices. They start out as an enchantment, but when certain conditions are met, they change into a land.
Whenever you grow the Rites of Itlimoc, a creature comes to your hand. The best part of the card is not there. When it flips into Itlimoc, Cradle of the Sun, things get better because it’s almost like having Gaea’s Cradle in your deck.
Zendikar Resurgent

Do you want to draw a card whenever you play a creature? There’s no need for the creature spell to work. Just cast it, and Zendikar Resurgent will replace it right away. But that’s not the best thing about this spell, which you already knew. With Zendikar Resurgent, the mana you get from lands is doubled.
You get two green mana when you tap a forest for mana. If you tap a Breeding Pool, you can add either green or blue mana to your pool. Seven mana seems like a lot, but in a game of Commander, that’s just the fourth turn.
Beastmaster Ascension

Green likes its animals to be big and many. Beastmaster Ascension shows this very clearly. This spell gets more powerful as long as you play creatures. When there are seven counters, all of your creatures get a power and toughness boost of five.
This is a huge boost for your side of the battlefield that will be hard for your opponent to stop. A 6/6 Llanowar Elf is not a small thing.