Ravnica Allegiance has been Constructed-legal on Magic Online since last Thursday. While players were cracking packs for the first time and battling with the new cards in pre-releases around the world, these new cards were already becoming battle-hardened in the MTGO grind. Theorizing about new cards and brewing decklists in spoiler season is one thing, but there's no substitute for real competition with prizes to wage war over. The crap gets cut quickly, so to speak, and the best of the new cards soon reveal themselves as the over-hyped fade away. It's why I had been eagerly awaiting the first release of Standard League 5-0 decklists, which have given us a treasure trove of information about Ravnica Allegiance Standard.

When Guilds of Ravnica was released online I wrote about its first batch of Standard decklists, and I was so struck by the success of green cards that I titled the piece "It's Easy Being Green in Ravnica." After pouring over the new decklists, it's clear that green has received another bounty of great new cards, and is again at the forefront of the metagame. Green was already the best color in Standard, so they have entered an environment ripe for them to excel.

Two of the clear stand-outs during spoiler season were Growth-Chamber Guardian and Incubation Druid, and they're the top performers in the first batch of decklists. Over the years two-mana creatures with powerful abilities have emerged as some of the finest cards in all of Magic, and it's a no-brainer that these were designed as serious Standard staples. Whether it is Growth-Chamber Guardian's ability to generate value like a Squadron Hawk or Incubation Druid's ability to become a massive mana source, plus both of their abilities to simply grow larger with adapt, these are valuable for nearly any sort of deck and strategy that can cast them. They can be found alongside each other in nine of the 29 decklists posted.

Growth-Chamber Guardian and Incubation Druid are excellent Magic cards because they stand very well on their own – they really don't need any help but mana. That said, they have tremendous synergy with +1/+1 counters. They are a great source of them, but are especially powerful when combined with other ways to add them. Growth-Chamber Guardian triggers when a counter added and Incubation Druid adds three mana when it has a counter, they don't actually need to be adapted. It's why the majority of the decks that use them feature ways to abuse this fact and get the most out of them.

Getting +1/+1 counters isn't too difficult, and in addition to new methods from Ravnica Allegiance, Standard already had plenty for creative players to apply. Take for example this Selesnya Tokens deck, which uses both Ajani, Adversary of Tyrant and Venerated Loxodon to add counters.

Ajani, Adversary of Tyrants is particularly great with the green two-mana adapt creatures because it can also reanimate them from the graveyard, which makes them a perfect match and a combination I expect to see a lot more of in the coming weeks.

Ever since adapt was spoiled, there has been a ton of hype over Hadana's Climb, and it appears to be warranted. It's a source of +1/+1 counters as good as they come, and it's perfect for enabling the two-mana adapt creatures. In addition to a singleton copy in the previous decklist, four more decks featured two or more copies of the card. One deck included the full four, an aggressive Elf deck that takes advantage of the Elf status of the two-mana adapt creatures.

The blue splash also opens up access to Incubation // Ingenuity, which adds some consistency to the creature curve while also giving the deck a removal spell that doesn't cut into the spell count. Another Elf deck splashed into blue, but takes a different approach, leaving Hadana's Climb behind.

This decklist includes a full four of the curious card Stony Strength, which at first glance might look like nothing more than a forgettable Limited trick but this deck demonstrates that it might be a new Standard staple. Triggering Incubation Druid for one mana – technically zero mana because it untaps Incubation Druid – is an incredibly potent play. I was fortunate to draft two copies of Incubation Druid in my first Magic Arena draft with the set, and the combo with Stony Strength won me every game I assembled it. Gilded Lotus is in the MTGO Vintage Cube alongside cards like the Power Nine to give you an idea of how strong it is, and Incubation Druid does a fine impersonation. Stony Strength ramps it into play as early as turn three. Once it does have a counter, Stony Strength can be used as a pseudo-Dark Ritual to get three mana from Incubation Druid for the price of one. It can potentially get even more mana from Marwyn, the Nurturer.

The payoff for all this mana is not an Elf at all, but Hydroid Krasis, which has exceeded expectations and broken out as one of the top cards in the set. It can be found in seven of the 29 decklists, where it acts as threat backed by tremendous value. As a mana sink that draws cards and gains life there's really no better comparison than to Sphinx's Revelation. The difference is that Hydroid Krasis also adds a threat to the battlefield, meaning no loss of tempo. While halving X may sound like a hard bargain, consider that it greatly outperforms Sphinx's Revelation at four mana, replacing itself but leaving a 2/2 behind – and in theory is better at six mana – drawing two cards compared to three, but leaving a card in play as a 3/3. At anything higher it's likely all gravy anyways, so I think this higher floor is more important than it having a lower ceiling. The point is that it's now one of the best cards in Standard, and it's going to change the way the format is played. In addition to being a great mana sink payoff for the Elf deck, its main home is in a variety of midrange decks. It gives these decks inevitability into the late game that will be hard for opponents to overcome. It looks quite good in this Sultai deck, which is essentially a Golgari deck splashing it.

Golgari can generate a ton of value and out-grind anybody in Standard, but it all comes from its creatures and planeswalkers rather than raw card draw. Hydroid Krasis fills this role by providing raw cards, converting the consistent land drops it generates from explore creatures into more resources. Better yet is that Golgari has ways to reuse creatures from the graveyard, so Find // Finality and Memorial to Folly are now more potent than ever.

One intriguing deck uses Hydroid Krasis's +1/+1 counters to its advantage in a deck built around them to make the most of Hadana's Climb, ideally flipping it quickly and using it to close out the game. It combines the two-mana adapt creatures with Wildgrowth Walker and the green explore creatures into a Simic Midrange deck built in the proven mold of Golgari, complete with Vivien Reid.

Adapt creatures also work very well with Rhythm of the Wild, which can add a counter with Riot. This superpowered Fires of Yavimaya has all the makings of a Standard staple, and the adapt creatures are only pushing it over the top. Growth-Chamber Guardian is an all-star in this very aggressive build with Zhur-Taa Goblin and Gruul Spellbreaker.

One use of Rhythm of the Wild is to give Prime Speaker Vannifar haste, and then give haste or a counter to whatever it digs up from the library. Birthing Pod showed the world just how good it was before being banned in Modern and Prime Speaker Vannifar brings a taste of that to Standard.

As you would expect, the deck is full of value-generating creatures, curving all the way up to Pelakka Wurm. Sailor of Means is a clever addition, and Mirror Image adds its own brand of value and versatility. Rekindling Phoenix stands out as a four-of, ideal for sacrifice because it reanimates itself, but also helping to give the deck a fair plan in itself because many decks will struggle with the large robust flying creature.

The new Ravager Wurm is a given here as a powerful and versatile creature to search for, but I did not expect to see the new Biogenic Ooze. It generates a token of value before turning into sacrifice fodder for Prime Speaker Vannifar, but to me it never seemed better than Regisaur Alpha or Trostani Discordant. As it plays out, Biogenic Ooze comes with the advantage of being a mana sink that can generate tokens turn after turn, and that's a valuable asset to have in a deck because it can completely change the late game. It also grows each token at the end of turn without any mana spent, so it's perfect for ending board stalls, and in a matter of turns will take over the game. These reasons are why Biogenic Ooze appears in four of the decklists, even up to a four-of. It appears that Biogenic Ooze is one of the big sleepers in the set and a card we will be getting familiar with.

Mana sinks like Biogenic Ooze and Hydroid Krassis benefit greatly from Growth Spiral, another new green staple. It's found in just three of the decklists, two which use Hydroid Krassis and Biogenic Ooze. Growth Spiral can also be found in a deck alongside Wilderness Reclamation, which many have called the most broken card in the set.

Rather than use Growth Spiral to ramp towards Nexus of Fate – which the deck just includes one-of – the deck instead uses it to build a massive Expansion // Explosion, potentially putting Wilderness Reclamation's ability on the stack floating mana and then tapping out again for a massive X-value. I love the additional plan of Murmuring Mystic, which gives the deck a way to chip down opponents into Expansion // Explosion range but also functions as a useful defensive tool.

Just like after Guilds of Ravnica was released, green is off to a headstart in Standard after the release of Ravnica Allegiance and the incredible amount of quality green cards it contains. The color really seems to have it all, from the aggressive and value-laden Growth-Chamber Guardian, the incredible mana of Incubation Druid, to the Sphinx's Revelation-esque Hydroid Krasis, and a ton of other role players in-between like Rhythm of the Wild and Prime Speaker Vannifar. Even control and combo decks gained a potentially broken tool in Wilderness Reclamation. The set has already and will continue to make a big impact on Standard, so the coming months will be exciting – and very green.