Is there any color that flavorfully gets more access to more "free" spells?

Blue, by a little (if you count making other spells “free”). We don’t do a lot of “free” spells.

Would a black spell or effect that lets you take control of a permanent be an acceptable bend? I know taking control is usually blue or red, but it doesn't feel like a break because black can already cast other players' spells.

We let black mess with other people’s stuff, but more often from the graveyard or their library.

re: "more regeneration hosers than regeneration effects" early removal spells were printed with "no regeneration" clauses because the primary use case of regeneration was to survive damage, such as from combat or a lightning bolt, rather than to survive a destroy spell

I don’t believe that was the intent, but it is how it played out.

"The issue is many players enjoy the higher powered designs of the straight to modern sets." I think there is a larger issue, but its impossible to capture given the character limit. There is an article from 2019 by Jeff Cunningham called "Lands and Spells" I would love if you could read just the section that starts with "I asked Randy Buehler once.." and ends with "Taking in the big picture.." ...Does the game designer have any business designing beyond what the most customers want? I think yes

I went and read the section in the article you mentioned. My primary goal as Head Designer is to make Magic the best game it can be. Market research (along with talking with all of you here) helps inform our choices, by giving us a better understanding of what the players want.Good game design isn’t just doing what the players want though. We need to surprise you and push the game in directions you don’t expect, but I am, and the rest of R&D, are negligent in our duties as game designers if we don’t have a good understanding of what the players interests in the game are when we plan out future designs.

Would the rules support a creature with no power in the P/T box, and only toughness? So, it would be unable to gain more power with pump spells or equipment? I was just trying to imagine the ultimate pacificist creature.

The rules require each creature to have power and toughness. It can be 0, but it has to be something.

Hi Mark! Bloomburrow looks amazing from the previews we've seen, hope you're all feeling pleased with the reactions. I had a question about Alania, the Divergent Storm - was the card originally designed to give "gift a card" to your spells? The wording for it feels really similar.

That’s where we started, but the rules/templating didn’t allow it, so we had to use slightly different rules text.

Are bite spells that can hit players in-pie for green? Obviously they're in-pie for red... Also on the topic of green spells hitting players (though largely an unrelated question), spells like Hurricane. Which is the bigger issue with them: Hitting players unconditionally being out-of-pie for green, or the "killing everyone" gameplay issue? I assume those are both significant.

They are not in pie for green.

Would something like ' counts as a token for spells and abilities' be possible within the rules?

My hunch given what I know about Claire D'Loon, Joy Sculptor is no.

Do you have any insight as to why the team for ACR went with "freerunning" as the mechanic vs using "prowl" and making the spells "kindred instant/sorcery - Assassin"? Obviously with the commander clause its different, but they've talked about how that was added later on.

We use kindred very infrequently.

If/When: Deciduous colorless enchantment spells?

Colorless is already deciduous. And enchantments are evergreen. So, I think it will happen. I’m not sure it will become a regular thing, but who know?