A lot of people look at this style and assume it’s a combo deck that wants to be Tron, when it’s fundamentally a control deck that plays more like Lands. And that assumption means that people often play it wrong, focusing on getting down an Eldrazi as fast as possible instead of focusing on neutralizing their threats and stabilizing first. (Unless, of course, you just have a hand that drops a T3 Ulamog.)

It’s first and foremost a control deck and actually plays more like a blue deck than it does like Eldrazi Post. Nearly 25% of the deck is dedicated to card selection: Ancient Stirrings is our Ponder, and we effectively run 8x copies of Demonic Tutor with Map and Crop Rotation. The big new innovation in this new list is the addition of From Beyond, which (besides making tokens) gives you the ability to tutor for an Eldrazi or All Is Dust.

Its combo matchups aren’t as bad as most people think, although they do require experience and tight play. The maindeck is set up to prey on creature decks an control decks, but Warping Wail gives C/G the ability to counter key spells against combo, and we have easy access to silver bullets like Bojuka Bog and Karakas (often at instant speed). Postboard, we have a plenty of tools like Trinispheres, Surgical, and TKS.
“2. The Candelabra based post decks are slow and have poor fast combo matches so they can be discouraging in fast metas.”

It’s not as bad as you’d think, especially after sideboard, and it really depends on the particular combo deck.

Sneak & Show is usually a favorable matchup as long as they don’t go Omniscience right into Emrakul. Karakas is easy to find, we have Warping Wail to counter Show & Tell, Needle for Sneak Attack and Griselbrand. They also have to be careful about a blind Show & Tell, since you have equally powerful threats to put in. Candelabra is very useful in this match because it can get you multiple Karakas activations vs Sneak Attack with >1 red mana. Postboard, you have Krosan Grips for Omniscience and Blood Moon.

Mono blue OmniTell, however, is abysmal. It’s beatable, but easily one of the worst matchups. Game 1, your only real out to Omniscience is to counter the Show & Tell putting it in (or hope they fizzle and just find land with their cantrips). It gets better after sideboard, but Omniscience is just a killer, since they have priority before you can Krosan Grip.

C/G is strong against graveyard-based combo too. Dredge is probably around 90/10, since you’re playing with 5x virtual maindeck Bojuka Bog (because of Vesuva) and 8x Demonic Tutors for them, Tabernacle to keep their zombie tokens away, and Warping Wail to kill Bridges, exile Ichorids, or counter Dread Return/Therapy. Reanimator is tougher, but still favorable overall. The only card you really fear is Tidespout Tyrant (and an early Sire of Insanity vs BR). You have Bog, Wail to counter Reanimate/Exhume, Karakas and Needle for Griselbrand, and Maze for all of them.

Turbo Depths is slightly favorable. You have easy access to Karakas and Maze, incidental lifegain from Glimmerpost to get over 20 and require multiple hits, Warping Wail to exile Safekeeper or counter Rite of Consumption. Ugin exiles Marit Lage for -0, and All Is Dust gets rid of her too. You can Crop Rotation for your own Stage to get a token in response to theirs (or just win if they lead with Depths) or you can Needle Stage. The only real snag is that you have to watch out for Ghost Quarter.

Storm is indeed a difficult matchup, but winnable with tight play and a little luck. In game 1, you can try to get them with Crop Rotation in response to Past in Flames, or try to fizzle them with Warping Wail on Infernal Tutor or a Ritual. They also have to go for Tendrils because you have Tabernacle for Empty the Warrens. In games 2-3, you bring in most of your sideboard.

In a really combo-heavy meta, you can also run Ancient Tomb to be able to cast Warping Wail off of a turn 1 Crop Rotation (or to play a turn 1 Sphere of Resistance).

C/G’s worst matchups besides OmniTell are Eldrazi Stompy, 4c Loam, and mono red prison. Chalice is really, really good against you because most of the deck are actually 1-drops. It doesn’t lock you out in the long game, but it does turn off your acceleration, card selection, and Wasteland defenses. When you add a clock to the Chalice, things start looking grim.

Eldrazi Stompy is particularly bad because it is immune to both Ugin and All Is Dust, making it much harder to stabilize. Maze + Candle is solid vs Eldrazi, however, and your odds go way up if you can land a Needle on Wasteland under Chalice. Tabernacle is usually pretty decent against them too, since it forces them to take a lot of damage from Ancient Tomb, can’t pay with Eye, and Temple only taps for 1. You have Ratchet Bomb and Krosan Grip in the board for Chalice, but losing your ability to wipe the board is tough vs an aggressive creature deck.

Mono red prison is similar with Chalice, and Blood Moon hits you hard in game 1. If they don’t follow it up with a clock, you can try to hit seven land drops for All Is Dust or eight for Ugin. I really like the new addition of From Beyond for this matchup, since it gives you a maindeck threat at cmc 4 that’s playable through a Blood Moon. Plus, you can sac the tokens for colorless mana to be able to counter Fiery Confluence. Postboard, this matchup actually got a LOT better under the new rules for Blood Moon. It allows you to play Depths with no counters, then immediately get a token when you blow up their Blood Moon. It’s still bad though.

4c Loam is just awful. They can tutor for Wasteland, and they can recur Wasteland. They have a fast clock. It’s the deck’s worst matchup, hands down. At least against Lands, their clock is slow enough to outmaneuver them. 4c Loam, not so much.

“3. Post lands should be looked at as a another color (colorless) and as such most mono colored Post decks should be treated more similarly to 2 color decks, dual color as 3 and so on; Legacy Post does not play like Modern Tron where eggs are used to effectively filter color and cheat on colored sources.”

So much this. In fact, this is why I came up with the name “C/G.” It’s not mono green, it’s colorless with a green splash!

The two things I think are important to get into your head first is that "this is a control deck first, combo deck 2nd" and "your first plan is to find one in the first place". As an example of a play that is directly opposing this philosophy, a lot of newbies do the turn 1 Pithing Needle on wasteland without knowing anything about the opponent's deck or considering what's in their hand. This falls into the mentality of the combo player where they believe their "win condition" is linear and has to be protected at all costs, and it opposes the "no plan" idea where you are making the assumption that you're going to do some kind of turbo ramp into primeval titan or some other card, when the correct plan very well could be to represent spells vs Storm or name Wirewood Symbiote vs elves to set up for a big turn with Show and Tell/Ugin.

According to mtggoldfish, the 5 most popular decks in order are Miracles, BUG Delver, Grixis Delver, ANT, and Eldrazi. It's common knowledge that miracles is unfavored vs 12-post (no longer an auto-loss with monastery mentor). One thing about the deck that I know will draw controversy is that the deck isn't as bad as people think it is. While I will definitely agree that the deck is probably never going to get past tier 2 or so, I notice that a lot of matchups that are commonly cited as god-awful are more often than not out of lack of experience, most commonly Storm and Delver (delver less so than storm). Even more weird is that some people may think that eldrazi is a positive matchup for 12-post, when in fact it's an unfavorable one. I guess what I'm trying to say is that a lot of people only really have a surface level knowledge of the deck.

With delver variants, the main problem people have is they go super-all in on a plan and then get instantly destroyed by a wasteland, force of will, abrupt decay, you name it. The most important thing is to play in a way where you're not begging to get exposed like that. For example, turn 1 cloudpost on the draw is a huge mistake because this gives the delver player the ability to continue developing their board AND wasteland your cloudpost. A much better play would be to play turn 1 tropical island, even if you don't have a play. This allows for you to have an opportunity to protect cloudpost later through crop rotation, or at least represent the possibility. Another example would be the stage where you want to resolve a Primeval Titan. I will usually cast a Show and Tell or Crop Rotation to force a response from the opponent, so that the real spell I want to resolve actually does. I have even show and telled with nothing to put in my hand before to try and force through a crop rotation for eye of ugin or for ugin himself. Of course you can't always play around everything. You can still lose to the opponent just happening to have 3 wastelands you can't do anything about, you can still lose to the opponent force of willing you when you really needed that one spell to resolve, but those are scenarios that you can definitely minimize your exposure to and you can definitely win games.

Storm is an especially unorthodox matchup where you're basically doomed to fail if you don't know what you're doing. The matchup isn't even an auto-concession g1 anymore if you run relevant spells like Trickbind or Warping Wail, which combined with Crop Rotation, forces your opponent to respect the possibility of fizzling. G1 is much more of a "disruptive ramp" plan (albeit not a very good one), while G2 is where you make a radical transformation into a "miracles deck". Eldrazi come out, primeval titan come out, show and tell come out, Eye of Ugin comes out, hell I even board out cloudposts on occasion considering how much of a liability coming in tapped is sometimes. The gameplan becomes one where you make sure you don't get destroyed by discard (countering those types of spells usually) and the super extended midgame is one where you have a sensei top in play and constantly float some counter on top to dismantle the opponent or at least buy you ~10 turns. Conventional ramp like primeval titan or show and tell are antithetical to the matchup since you are tapping valuable mana that can be used to protect yourself, it's too slow, and if you get a primeval titan in the lifegain is honestly a joke since by the time that happens, you've given your opponent all the time in the world to sculpt the perfect hand and dismantle whatever situation you're in regarding your hand and life total.

These are examples of matchups that wildly differ and there will be more examples of crazy scenarios where you have to really think outside the box. With the steep learning curve of the deck and this deck basically being 3-5 decks at once, it's safe to say that I have enjoyed this deck for a few years now and I'll probably enjoy it for years to come. I really hope you can come to share a similar sentiment if you decide to pick this deck up.