Hello y'all, I normally don't write about Magic: the Gathering on Axes and Orcs. I apologize for this brief interruption.
It's been roughly a week since ProTour Amonkhet, and I'd like to take a moment to do a bit on something that is extremely important to playing MTG, your manabase. I am focusing on the various Aetherworks Marvel lists, although this also applies to any list running any form of basic land fetching.
The other day I was watching Paul Cheon (HAUMPH) streaming. He decided to stream Temur Marvel as it was one of the best represented lists at the PT. Instead of copying any of the lists, he was cherry picking from the various highly placed lists. Why is this problem? It isn't. Paul is a pro, unlike me. However, I noticed that he was mismatching the manabase he was building with the other cards he was including. It is my personal rule of thumb that when you are running spells that fetch basic lands you include one basic for each mana symbol in the casting cost for you spells. This means if you have RR in a single card, you have at least two basic mountains. The only deviation is basic forests, as almost all the basic land fetching spells are green, you want a higher chance of drawing green sources so you can fix your mana.
But why should someone listen to me, a non-pro? You don't have to listen to me, but you might want to pay attention to the pros who took Marvel to the PT.
First, let's compare Yuuya Watanabe's and Martin Müller's lists.
Watanabe has a single mountain and none of his spells require RR.
Müller has two mountains and has Chandra, Flamecaller and Sweltering Suns, both of which require RR. But does it matter that he has four Chandra and two Sweltering Suns? Let's look at other PT lists.
Eric Froehlich has a single mountain, no RR in his maindeck, but he does has a single Chandra, Flamecaller in his sideboard. I don't agree with that, even though it's one card if only because the opportunity cost of cutting one of the duals for a mountain is relatively slim, but it is only a single sideboard card unlike Müller's four maindeck and two sideboard cards.
But let's look at something completely different, Jiachen Tao's Four Color Marvel list.
It has WW and UU and has one island and two plains. Interesting, yes? He obviously wants to be able to cast Fumigate, but is willing to wait a while to cast Memory since it's a late game card that doesn't clog up your hand, merely resting in your graveyard.
Huey Jensen's Sultai Marvel list is spicy.
He has not only BB but BBB cards in his 75, and look he's running three swamps, even though he has two Evolving Wilds, four Blooming Marsh, and four Aether Hub, clearly he, and Reid Duke who also had Demon of Dark Schemes maindeck, felt that having three basic swamps was important. Brennen Decandio and Julian To were also running Sultai Marvel, but only had a single Demon of Dark Schemes in their sideboards, and only two swamps.
If you look at the rest of the Aetherworks Marvel decks from Protour Amonkhet, there seems to be a consensus that if you are running double color in a casting cost you have two basics, unless it's a small number in the sideboard or a card that doesn't need to be cast on curve.
I encourage you to check out MTG Goldfish, which is where I made my screen captures of the decklists to check out the lists for yourself, and don't cherry pick good cards from similar lists without double-checking your manabase.