Just curious, what exactly is Pioneer?

A brand-new format just announced this morning. Every standard-printed card from Return to Ravnica forward, except the fetchlands from Khans of Tarkir. https://magic.wizards.com/en/articles/archive/news/announcing-pioneer-format-2019-10-21

Honestly, I think you need to trim a couple non-creature spells to make sure you CoCo actually hits things consistently. Otherwise, awesome deck!

It will really depend on how much cheap removal is floating around in the new meta. In Modern, I ran this deck with the same 12 spells (just with Vines of Vastwood in place of Blossoming Defense ) and it wasn't often that I would whiff on a CoCo. Without Lightning Bolt and likely less Fatal Push , Pioneer already looks more friendly towards this sort of deck, so I might be able to trim down on the Blossoming Defense and Aspect of Hydra totals if that's the case.

Oh wow, pioneer doesn't have lightning bolt in it. Haven't realized that yet, I don't know if I even want to try the format anymore, I don't know if I've built a deck without bolt in it

i like your current build of the deck, although i would probably wouldnt put ooze main board thats just me. cause your a deck that wants to constantly be using its mana and taping out most of the time. also 100% need veil of summers in your sideboard 4 of

Scavenging Ooze is a very matchup-dependent card, and I've mostly got two in the mainboard because I'm unsure of what the meta will end up balancing out as. My initial worry is that we'll see both a lot of aggro (as every new format seems to bring) and a lot of graveyard strategies based around the SOI block cards, both of which scooze is a wonderful card against. If we end up with a score of midrange or control strategies, it definitely gets much worse, and I'll probably swap it out in the mainboard with Prowling Serpopard . As for Veil of Summer , I had it in here at first, but took it out when I considered what MangaVentFreak13 said up above: CoCo wants you to play very few non-creatures, which pushed me towards relying on Prowling Serpopard and Blossoming Defense instead. If Dimir-colored decks end up being extremely oppressive here, it's definitely something I need to consider again, along with adding more serpopards and perhaps Witchstalker . Thanks for the suggestions!

Even though the deck is built around mono green devotion, 4x Nykthos is a terrible idea because of several reasons.

1) Obviously, the legend rule which means drawing more than one sucks

2) Most of your spells have symbols only, which means the mana from Nykthos's first ability is useless a lot of the time

3) Nykthos is slow. You need at least 3 lands total to use its second ability. And you probably want to be dropping this turn 3 because it's useless turns 1-2 (unless you play scooze t2). Because you need a higher critical mass of lands to get use out of Nykthos, this means that having 2 nykthos and 1 other land is just way worse than having 2 flagstones + 1 urborg in a smallpox deck, for example.

So basically, even though some decks run 4x of legendary lands, this is a really bad idea with nykthos. I'd run 2 at most.

I agree, I've been going back and forth on how many to run, used to run 2, upped it to 4 for testing, but you're right that it's truly just a dead card if I get a duplicate, so 3 definitely feels like the upper limit for it.

I mean by the time you have the nykthos mana engine going, the actual mana you get probably isn't that important because the main limiting factor is card draw. The only mana sink you have is Rhonas, since imo scooze is too situational and limited by the number of creatures in graveyards. This is probably why a lot of mono green devotion stompy lists choose to cut it entirely.

What do you think about the new Werewolf Pack Leader ? I think it's an automatic 4 of since it's a nice 3/3 on a and also draws a card every turn which is really good.

I hadn't seen this spoiler before, absolutely 4 of easy, like you said a 3/3 that gives us GG devotion early, starts drawing us cards (a major shortcoming of this deck), and becomes a bit bigger with trample when our Castle Garenbrig s or Nykthos, Shrine to Nyx start to come online. This most likely just replaces Barkhide Troll , and probably knocks Avatar of the Resolute down to 3 since it doesn't trigger Avatar's pump ability the way Troll did. WotC giving this list some incredible love with this card.