Hi Mark, there's lots of cards from the ABU/Arabian Nights and Antiquities sets that lore-wise should be legendary by today's standards. Though I know the reason is that the Legendary mechanic was introduced in Legends, so after those sets were released, was there any intention of retroactively making erratas on cards that would have been Legendary if released in a post-Legends set?

No.

Will any of the Arabian Nights cards like Ali from Cairo King Suleiman or Aladdin ever get an errata to make them legendary? I’d really like to make an Aladdin commander deck

There are no plans to add legendary to cards pre-Legends (which introduced it).

Can you own Once Upon a Time or Happily Ever After by the name alone? Wizards retroactively invented a Rabiah setting that isn't identical to the source material - a world of 1,0001 versions of the plane, complete with planeswalkers, and names like 'Juzam' and 'Ernham' are, as far as I know, original to Magic. Aside from one or two real character and place names, it seems as distinct as Eldraine (though as a world rather than a set of references I'd argue Eldraine lacks coherence).

Names of cards isn’t the issue. It’s name of characters and places (and to a lesser extent famous objects) that matter. Let’s say we wanted to visit Rabiah in some other media, we could only reference things uniquely ours like Juzam Djinn. Note that every character, anything that would have bern legendary if legendary existed in Arabian Nights uses the actual name of the characters straight from the source material.

What is Homelands called Homelands. I believe it is the only set that is not second or third in a block that does not reference the plane it's set on

It was at a time when we weren’t doing tons of sets in other worlds, so we hadn’t really hit on the “put the plane name in the first visit” idea. I think the name represented that Serra and Feroz we’re making a safe zone. I’m not sure though.Tempest is another example and one could argue Arabian Nights.

"Portal: Three Kingdoms took place on an unnamed plane that shares a lot with early history China, but is not China." Including the names of a bunch of Chinese historical figures? It seems like a weird choice to insist it was some other multiverse plane that looked so much like Han dynasty China that the people even had the same names.

Both Arabian Nights and Portal: Three Kingdoms borrowed strongly from existing story elements from the source material.

Help me understand the mental gymnastics: How is 1001 Nights not ok to use, but Grimm's Fairy Tales are just fine?

A world inspired by a real world source is great. If we wanted to create a brand new Magic world inspired by 1001 Arabian Nights, that would be a cool world. Arabian Nights though is not that. It is a straight copy of everything. There isn’t a card capturing the trope of Aladdin, there’s actual Aladdin.Throne of Eldraine, in contrast, is making a lot of fun use of tropes, but it gets to play with them and position them within a larger world that is uniquely our own. Eldraine isn’t exactly Camelot or Grimm’s fairy tales, but a brand new world using those sources as inspiration to create something uniquely Magic.That is the difference.

Hi MaRo! Is Alpha all the way up to Revised set in Dominaria? Or was it retconned to have cards and lore from differebt planes like the later core sets?

Early Magic sets (past Alpha) didn’t explain what plane they took place on. The creative team in the early days (called Continuty) ended up labeling some sets as taking place on other planes (such as Arabian Nights being on Rabiah).

Could we possibly get another Arabian Nights-esque world that isn't Rabiah, since we can't go back there due to public domain stuff?

It could happen.

P3K's existence predated the usage of "when" for Zodiac Dragon, and you say that it's not functional errata in spirit, because the literal text doesn't match how the card worked then. YET, Arabian predated the legendary supertype, and you claim that giving them "legendary" *would* be functional errata? I don't get it. Clearly the spirit of those cards is that if they were printed with legendary available, they would have. And I bet 99% of players then had 1 copy of cards like that to play with.

There is a big difference between unified templates across all of Magic and understanding what we might have done if certain mechanics existed at the time. The only way to know if an Arabian Nights card is legendary, for instance, would be to know the source material and know wether or not it referred to a specific character. For example, is The Old Man of the Sea a specific character or a type of character? (He’s a specific character, I believe). In short, we expect players to grasp that all the cards work similarly, but not that a card might have secret abilities that reading the card can’t easily clue you in on.

People keep talking about the storm scale and the Rabiah scale. What do these mean?

The Storm Scale is about how often an attribute, usually a mechanic, is likely to return to a Standard-legal set. 1 is very likely and 10 is very unlikely. The Scale is named after the Storm mechanic which is unlikely to return. The Rabiah Scale talks about how likely we are to return to a particular plane/world in a Standard-legal set. Again, 1 is very likely and 10 is very unlikely. The Scale is named after Rabiah, the plane of Arabian Nights, somewhere, due to its lack of deviation from the source material, we are unlikely to return to.