First of all, I'm so happy to hear back from you! I still remember you from the Viking set we were working together on Discord a few years ago, the one that was essentially killed by Wizards announcing Kaldheim, a real Viking set. I still have all the files of that set: cards, story plans, maps of the world we were building, etc... that never went public. I also remember a lot about you as a person, including your real name, where you're from, and which Italian thing you were a fan of. My first instinctive reaction as I saw the notification of your tag here was innerly screaming your real name as if I had heard back from an old friend after years... well, that's kind of what this actually is. Then I saw the specific thing you want to work on, a four-colored set and world. I'm sorry to say it, but that turned me down a little bit, and now I will explain why.
You might have read about my huge story plan that I'm working on in my spare time. It's a big spreadsheet with planeswalkers in its rows and sets/planes/stories in its columns. Currently it's 37 columns, corresponding to that many custom sets, making up six different story arcs, and spanning 19 custom planes in their own multiverse separate from the official one. I think you know about the first one of those planes, that's called Vukanat. It's the one I'm talking about in
Round 3 of last month's MCC, which I hosted, and the only one I've written a full novel about so far. Only a few carefully selected people in the world have that novel, and you might be among those, I honestly don't remember now. What I clearly remember is talking about it with you on Discord back then and sharing details about that world and the protagonist(s) of that story. You might also remember me talking about a custom Merfolk planeswalker of mine, and us planning to make the Viking world we were working on his home plane. He's still in the table, and still the same character I talked to you about, and his name is still the same one you helped me come up with. Our Viking world is no longer his home plane, I changed it after Kaldheim killing our work, but his motivations and traits are still the same. Another world inspired by our first idea (later rejected) for our Viking set is also in that table, though set on a world with a different flavor inspiration. I don't think I've ever talked publicly about that one.
I have very fond memories of both you as a person and working with you on a common project, and I'd be ready to do it again right now, but I'll be honest with you: not on this specific subject. With so many planes in my table, you can probably easily guess that a four-colored factioned one is already in there. If you've ever read the name Kolyfar in my posts, that's exactly what it is, and I've already made preliminary work on it. I know which approach I want to take to try to make it viable, I know the name, philosophy, and mechanical focus of at least three of the factions and I have ideas for the other two, I know what comes before and after it and how it fits into its own story arc, I know which of my custom planeswalkers are involved in its story and what their roles are... In short, I'm already far too deep into it to work on another different four-colored world. I'd really love to work with you again on a different project though, one that doesn't overlap with an existing column in my table or that if it does, at least is not yet defined as much as Kolyfar is, and there are several of those farther to the right in the table.
I'm really sorry to have to turn down your offer, but please do not hesitate to contact me at any time to work on something different. I do have something to offer you though:
a link to a post in the DCC discussion thread where I share possible land designs for a four-colored set aimed at letting you play four colors without everything degenerating into five-color soup, which is my aim with Kolyfar. You're free to take inspiration from those, or from my four-colored designs from the DCC. I just finished today to post there a huge four-color cycle every other day in the last two months. Feel free to also check that out and use ideas from there.
Many thanks for the offer and a big hug from Italy! I hope it won't be years before I hear from you again.