While that seems to be the case (rulings of Biovisionary for example), I think it would be pretty easy to assume that all these bides would go onto stack at end step, then you would order them so that this would resolve first, meaning that another that was tapped would get its bide effect procced. The design is seemingly indicating that usage after all, but since that isn't possible, it really shouldn't do that. Cards should intuitively point to the correct ways of playing.

No, it doesn't trigger the others, because by the time this untapped them there trigger is already passed.

This helps to proc your other bide dudes, right? As for the flavor, I would assume that a mathematician would actually untap artifacts and maybe enchantments (contraptions and theorems) instead of people.

Well, the rule could always be adjusted to include intrinsic abilities. I don't believe there's any other types that have a color tied to their intrinsic ability.

SecretInfiltrator is correct indeed it seems.

> 903.5d A card with a basic land type may be included in a Commander deck only if each color of mana it could produce is included in the commander’s color identity.

That's seriously messed up. Why don't intrinsic abilities count when it comes to determining a card's color identity? That would seem to me like a much better solution, even regarding future design, rather than this 903.5d "exception rule".

Personally, while I like the Tainted cycle, I want to do something that plays up the color's identity, like caring about white things (as opposed to just caring about Swamps). So I'll iterate and try out different designs, but I'm for sure not going to use the tainted cycle as a template and just make 4 (opening the road for 20) "tainted" cycle lands.

That being said, I forgot that Plains aren't actually white, which is an issue. I could dial it back to say "White permanent or a Plains", or I could have it always enter tapped but provide another bonus for controlling something white, like "gain 2 life".

Color identity seems so easy. Though (basic) Plains won't work.

Due to one of the more confusing rules issue these are going to have any Plains (even nonbasic) will not necessarily have a white color identity (Mistveil Plains being the one exception as of this writing) but there is a separate rule excluding any Plains from a Commander deck unless white is in the commander's color identity.

This may lead to misconceptions about the way this card plays.

Really, if it were up to me, I'd simply make a white pendant to the tainted cycle (Tainted Peak etc.)

This is what I get for making changes before bed again.

I think if I'm going to use reminder text for color identity, I think I'll go for the second one you proposed, shortened somewhat. Something like

>(A permanent's color identity is white if it's white or has in its text. This includes lands.)

I think I'll hold off on having odd color identities in this set, since this focuses on Rome's pathway to empire. If this gets a 2nd set, it'll be focusing on the transition to Empire and Rome's heyday, so there'll be some room to have white-identifying other cards in there to represent Rome-assimilated provincals.

Your example isn't my favorite example - the best are the Llanowar Goblins that you mentioned. If I were to use color identity as a major theme, it'd be for designing hybrid cards (i.e. Dryad Militant or Curse of Chains) that have effects that could belong in either color (without the crazy color commitment flexibility), or using a [BASE COLOR MECHANIC] in [COLOR IDENTITY] ways, such as putting Evolve on Mikaeus, the Lunarch or putting Haste on a wall with a tapper ability.

"... can lands that can... " missing a word there. Color identity is admittedly a bit tricky to have remainder for...

> (Lands that have in their text, including basics, have white color identity.)

Going with color identity means that you probably should mechanically use it elsewhere in the set as well. So coming up with a reminder text for color identity is likely required:

> (If a permanent is white or it has in its text, it's color identity is white. This includes basic and nonbasic lands.)

>(A card has the color identity of a color if it's of that color or the color's mana symbol appears in its text. Basic lands have the corresponding color's color identity.)

?

I wouldn't bother talking about exceptions such as of not counting the mana symbols that appear in the reminder text.

As far as what to do with color identity, here's one example that could utilize color identity counting cards or whatnot: "[DOM] Llanowar Goblins". While a bit gimmicky, I could see cards that function like white cards, but use another color's abilities to implement them and also cost mana of that another color - but still "identify" as white cards. Or more flavorfully inspired designs like those "Llanowar Goblins".

That definitely sounds like an elegant way to reference permanents that go in White decks. I'll try it out, see how it goes over. It actually might make these cards playable in a constructed environment too.