The sixth sect. The only identity they have so far is that they're multicolor, yet cohesive, and not divided. We also know (I think) that they consist of "normal" creatures, like elves, humans, merfolk, vampires (?), goblins, etc.
I suggest they have a keyword mechanic to themselves, possibly something that plays along with having multiple colors. "Multicolor creatures get +1/+1" is simple, but probably too much to have in spades. I suppose we could have an ability word, like landfall or metalcraft, but I like the idea of a keyword. That way it can be interacted with and has rules meaning.

Sounds good. I'll try to think of one.

Strangely, "Multicolor creatures get X" is probably the wrong approach. We have 5 linear mechanics coming down the line... I assume we'll want to have one or two very modular mechanics in multicolor to make up for it.

Are there any mechanics that easily end up in all 5 colors in Magic that can be exciting? (or all but one? This is multicolor after all.) Something like cycling, perhaps, but not that stiff? Can we make something up? Can we do it in a way that it feels like a normal Magic world would have access to this?

And for that matter, by calling this a "normal Magic world" are we setting ourselves up to make a boring plane that's being invaded? Shouldn't this place have some gimmick, besides "Magic Base".

I think if we can find a way to make the natives actually consistently multicolour, and feel like it, that'd satisfy the criterion of not feeling like a boring plane. So I suggest we try to find a plausible mechanical identity that could link (some reasonable proportion of) the gold cards, and let the flavour relate to that.

Thinking about the solid gold set Alara Reborn, we cooould make it Alara that's being invaded by the five factions. But if we want to avoid that, then to me, gold implies cosmopolitan civilisation.

When you say a mechanic that's in all-but-one colour, that makes me wonder: could we have it that the natives all have flying? And the monocolour creatures generally don't? Any gold card can have flying. And flying is a lot more exciting than cycling, which is a flavourless gameplay-smoother. (I absolutely love cycling, but it's not something to base a flavour on.)

Perhaps the toughest bit of this proposal is that monowhite and monoblue commons (and rares) would have no flying at all. I'm not sure if that's remotely plausible.

Yes, that's a clever one. This could be a cloud city with everyone flying about. Since multicolor would be, at best 40% of this set, that would be the maximum percentage of creatures that could fly. It could also do some funny things to a draft in this environment. Did you go 100% mono-colored? How do you plan to handle these flying creatures? Perhaps you should find a way to sneak a little Green (!) in your deck.

I'm cool with it, and it doesn't even have to be our mechanic. Just a nifty aside. The only strangeness is "If all the creatures are flying around, and the invaders can't do that, how the heck are they being invaded?"

I like the idea of flying (and something else) being shared by the multicolor cards.

We still don't know for sure how the tribes should match to decks. It may be the case that not ALL the monocolor cards are invaders after all, just most of them; or you may have hybrid, gold, or artifact creatures that can be cast with blue mana (a bit like how the borderposts fill the mechanical role of dual lands while unarguably being multicolor permanents).

Well, the fliers could have their food on the ground. Also, that was kind of what I was trying to get at with Good for mono or multi.

I do love the flavour of a cloud city. I enjoyed the Soratami and Oboro, Palace in the Clouds; I've contemplated making a Magic set with a sky city theme myself. So I'd be very much up for that being (one part of) the identity of multicolour here. Having the monocolour decks try to find some green to get reach is an amusing strategic consequence.

I'm still nervous about whether we can actually make a full sensible set of monoblue and monowhite commons without any flyers, but it's a compelling enough distinction that I'd like to try.

I think we've give up hope of limited being anything near whatever "normal" is.

Well, if we went with my suggestion on Mono Blue about flooding, Blue wouldn't need flying. It would have a high incidence of islandwalk. The other colors could obviously have some landwalk,too. I'm sure nothing's stopping enchaments or something from giving the creatures flying, either, and they are other alternate forms of evasion. Intimidate is probably an interesting choice. And maybe there can finally be a few more plainswalkers.

I vote for trying flying city as well.

It would indeed be ironic if green is the best defense against flying, but it definitely amuses me. One option for white/blue is to give them reach (or possibly contingent flying?) which is unusual, but makes sense if they normally have flying but don't. I don't imagine we want a lot of "Plainswalk, reach." creatures but that sort of equates to flying :)

There's a handful of white reach guys as precedent, although it hasn't happened since Longbow Archers in 7th Edition. Landwalk and intimidate are fair alternative means of evasion; white has a minor history with intimidate via the Seeker ability too.

Of course, Innistrad has at least one white creature with intimidate, as well.

I thought someone's "can block creatures as though they had no abilities" was ingenious, and I think that's clearly white, so there could be some of that, which is what I was thinking of when I considered giving white reach. I think giving white/blue reach wouldn't be the best thing, partly just because it's doing the best to make the change not matter. But I don't think it would be inappropriate whether they've had it before or not.

Come to think of it, blue's had one "U: tap target creature with flying" which would be a very blue anti-flyer ability.

White can also get plenty of "target attacking creature", which may fill the gap (with or without specific mention of flying).

Red and black can probably cope :)

Let's continue that specific discussion on How can monocolor deal with flying?. What else do we think multicolour should have?

If people are up for the flying idea, then that's definitely one major mechanical hook. But we will want a bit more than that: some minor themes, perhaps, and at least some creature types.

Multicolor.

Sorry, couldn't resist. For the normal vs. weird contrast, I think Elves, Goblins, Humans, and Merfolk. I always liked the Leonin personally myself, and Vampires seem to be the new "generic" black tribe.

I'm up for the flying idea. We can't give EVERYTHING flying, but a majority makes a nice cohesiveness.
For creature types, I'm thinking humans, elves, and merfolk. Probably aven, since it's a flying plane. Probably goblins. Also, can we have a lammasu? It's only on one creature, but I think it's a cool type.
As for minor themes... Well, we could have several cards with "Multicolored creatures you control have..." and "Whenever you cast a multicolored spell..." Those are the obvious ideas. What about some sort of mechanic that allows you to swap creatures you have in play with ones in your hand? Something like ninjutsu, only less ninja-esque. (This is just me thinking out loud.)
EDIT: The point of this would be to help when you don't have exactly the right mana.

Rourke posted while I was typing. lol

I forgot about Aven, that would be perfect. Maybe an equiptment sub-theme for humans, goblins, and elves? If the don't have wings, they have to get from one place to the other somehow.

The "cloud city" seems to be slightly at odds with the "normal plane" feel, though. What would it feel like to have a bunch of gold flying elves and gold flying goblins? If the only goblins and elves are multicolour, in fact?

It could work; it could be fun. It'll definitely turn people's expectations upside down, though.

Some effect a bit like ninjutsu was mentioned somewhere else, and sounds good to me. And I certainly think it's good for the gold sky world to have a bunch of established-but-unusual flying creature types like Lammasu and Manticore, as well as Aven (who have type Bird) and Sphinxes and Merfolk and so on.

I pictured winged elves, myself. Lorwyn elves had horns and hooves, so why not? Humans are seen as adaptable enough in fantasy media that I think some of them would have ways of flying without outside assistance, at least in card form. Goblins probably need help, though.
I don't know if equipment needs to be a sub-theme, but it can definitely be there to help out.

I think it's more interesting with existing but underused types, like leonin and lammasu. And yes, aven, if we want lots of flyers (I like the idea of all, even if it doesn't turn out that way). If none are mono, there's less reason to use the traditional mono-coloured tribes.

Old keywords that may seem "city in the clouds"-y:

• absorb
• mana fixing ("return this creature to your hand, add one mana of any of its colours to your mana pool?")
• Changeling
• Entwine
• Evoke
• Forecast
• Landfall, Fortify
• Phasing
• Rampage
• Splice
• Sunburst
• Radiance
• Divinity counters?

I assumed artifacts and equipment would have to fit into either mono or multi decks; it may or may not be concepted from the central plane.

I'm all about subverting expectations.

Are leonin really underused? They're in Mirrodin, Alara, and core sets. There's even a leonin planeswalker.

OK, not very underused, but used much less than elves and humans :)

For the ability, I was thinking about something that swapped upon entering the battlefield, to distinguish it from ninjustu.
I have class until five, though I would rather stay and work on this. :(

Not sure this needs an ability as much as other things might. We only get four mechanics, and we (probably) already have Dedication, Enchantment Creatures, and a returning mechanic.

But enchantment creatures are a sort of gimmick mechanic, in that they don't require any new rules text. They're like the colored artifacts from Alara. Do they really count toward our limit?

True. And this could be the returning mechanic as well.

I don't know what we want to use here as a second mechanic. I just want to keep the reminder going that we probably want it to be modular. Abilities like Sunburst make a lot of sense thematically, but only really work with multicolor.

I admit, that's easier said than done. Creating modular mechanics for an expressly multicolor guild is a daunting prospect. I have noticed that, so far, there doesn't seem to be any one mechanic that screams "I'm a 5-color mechanic."

jmg: good point.

I think Cascade was a mechanic that was nicely modular while fitting all five colours.

The Shadowmoor design team also took advantage of the way that persist was new to give persist to all five colours, and persist is fairly modular.

To represent the Aerans being more "advanced" than the Monos, maybe the can have some sort of card-drawing subtheme. Not that card drawing will be absent from the mono colors, but it's a thought.

See Aven Seer And Aeran Priest for my ability word proposition.