Re the person asking for a keyword meaning ""this object is all colors". While it's not a keyword, 3 cards like that exist. Transguild Courier from Dissension, Sphinx of the Guildpact from Ravnica Allegiance and Fallaji Wayfarer from the Painbow Dominaria United Commander deck.

FYI

I was very disappointed to see that Gandalf the Grey wasn't colorless. Do you know why he wasn't? I understand why he needed a broader color identity but I feel like that could have come from an activated ability. Alternatively he could have had text saying he was colorless and given a Grey frame similar to how transguild courier has a gold frame. Noneldrazi nonartifact colorless cards are very fun and Gandalf is the perfect candidate

We have to be careful not to do things that are funny to read, but don’t play well. A lot of players will want to use that Gandalf as a commander which becomes super hard to do if he’s colorless.

I think where someone falls on the question of changing how hybrid works in Commander really reveals whether they fall on the Vorthos/Mel spectrum. Mels see the change as playing into logical mechanical space and Vorthoses see the change as violating an important part or the flavor of Commander.

I get the “I’m used to things as they are” resistance to the change. I don’t quite get the flavor part though. A commander is certain colors. Why are they resistant to things that they can cast using only colors they have access to? Why is a red/green mage against using a spell that can be cast with only access to mountains? Philosophically, for instance, what is so wrong with casting a Transguild Courier? You can cast any other golem. Why is the fact that this one is five colors, definitionally, not in casting requirements, make it something from a flavor standpoint that’s unthinkable to ever cast (unless you’re five colors)?

FYI You can run Transguild Courier exclusively in a deck with a 5c commander, but Planewide Celebration (which makes 5c tokens), can be run in any deck with green in its commanders color identity since colors aren't checked unless they're the mana symbol itself or a color defining ability for the card.

Interesting.

FYI Transguild courier falls under the rule where characteristic defining abilities and color indicators add to a cards color identity.

Can you play Transguild Courier in any deck or just a five color deck?

Devoid is a neat mechanic. I like the idea that creatures and spells can be mechanically a colour, but not be that colour. I was wondering if the opposite can be true. Can a non-artifact creature be colourless and still be any/all colours?

Transguild Courier costs generic mana, but is all five colors.

Why isn’t there a 5-color color indicator on Sphinx of the Guildpact?

We couldn’t find a color indicator that looked pleasing and worked for color-blind players so we reverted to rules text. Transguild Courier has likewise been updated in Oracle.

Re: Transguild Courier, For a better example of color identity rules being dumb, you can't use Noble Hierarch in an monogreen deck, but Birds of Paradise, which taps for two more colors, is a-ok. Or how creatures with extort are fine in monoblack or monowhite, but if you printed a card that functionally had extort, but spelled it out instead of being a keyword, it suddenly becomes WB.

Thanks for the examples.

Hybrid in commander: I believe the the thing the rule committee is looking at is that in every zone it both colors. If a U/R hybrid cards is on the battlefield it is both blue and red for things like devotion and protection and whatever else cares about the color even if it's in a mono color deck. Personally I agree with you that it should look at "can the commander you choose cast the spell" but they at least have something to back up their position.

Yet you can play Transguild Courier in any color deck even though it’s all five colors. The color of the permanent is not what restricts it.

You're probably going to get a flood of this, but Transguild Courier is only legal in 5 color commander decks. Its rules text is the equivalent of a color indicator, which factors into color identity.

When I learned the Commander rules many years ago, that wasn’t the case. While I dislike the choice as least it’s now internally consistent. That’s an improvement.