Is the relentless rats ability transferable? Could Card A allow any number of Card B's in a deck?

I think the rules would allow it, but it would need flavor to make sense. The larger problem is that it creates a deck situation that might be illegal without a way for an opponent to confirm. You see five copies of Card B, but haven’t seen Card A. How do you know if your opponent has an illegal deck?

Question about the relentless rats/nazgul rule: Can a card in a deck remove or alter another's limit? Or does it have to be printed on the card itself? For example, "If X is your commander, your deck can have any number of cards named Y"?

We played around in this space in Time Spiral design and it gets mucky in the rules pretty fast.

Hi Mark, may I request a wolf card with the relentless rats/nazgul ability?

You may.

You mentioned in today's article that the Relentless Rats ability can be in any color. Was that something the Council decided right away, and if not, which color(s) did you consider keeping it in?

It’s more a tool than a mechanic, like say hybrid or double-faced. All colors can have access to all the tools.

So, it seems the question about why Relentless Rats and similar creatures don't have the "basic" marker has come around again. Personally, I have finally gotten to where I do understand why the two functions are different (even though they're similar), I have to ask: with so many people always assuming that's how it works, is there any consideration to using the "basic" supertype on creatures and changing the rules to simply mean "you can have as many in a deck as you want" to fit the player's expectations? thanks!

I already answered this today, but I’ll throw in a new reason. The danger of combining two things into one (basic being a marker and a signifier of being unlimited), is that it combines those two things into one mechanically, making it harder to refer to one and not the other. Finally, matching player intuition is making sure players don’t play the cards wrong. Basic not meaning what some more enfranchised players think it means doesn’t actually cause anyone to play anything wrong, so there’s little gain here lining things up to that perception, as it comes with other baggage we don’t want.

Mark, was there ever any consideration to giving the "You can play any number of " cards like Persistent Petitioners, Relentless Rats, and Dragon's Approach the Basic supertype, then expanding the rule that lets you play any number of copies of a Basic Land in your deck to include any card with the Basic supertype? It would allow you to save a line of rules text for these kinds of cards.

But it causes different issues. Basic means other things than “you can play more than four”.

Why aren't Relentless Rats and other such cards Basic? Is it just less confusing?

Because being Basic isn’t the thing that lets you play any number of basic lands.

What do you think is more likely: white using token making to get a Squadron Hawk type effect that actually worked in Commander, or white getting something more akin to Relentless Rats?

Both could happen, although the token version would be French vanilla.

If or when: Basic supertype for creatures such as Relentless Rats and Shadowborn Apostle?

If. The Basic supertype is not what lets you play any number of a card.

Will abilities that allow you to have an unlimited number of a card such as "Relentless Rats" ever be keyworded? (Or would they get the "Basic" super type?)

I doubt we’d keyword it as we use it infrequently. Also, that’s not what the Basic supertype does. .