Comprehensive Rules Changes
103.4 and many more!
It's the London Mulligan! First tested in London, now at kitchen tables and tournaments near you. The big block of text you read in my Release Notes is 103.4, then another half dozen rules had tweaks, including the multiplayer rules. In case you've been wondering and haven't seen my Twitter feed, the answer is: the first mulligan you take in a multiplayer game doesn't count when determining how many cards to put on the bottom of your library.
What happens if you add snow mana to your mana pool? It melts. You get one colorless mana, and that mana probably wasn't produced by a snow source, so it probably can't even pay a snow cost. (I'm looking at you, Elemental Resonance, you're the cause of all this.) Snow isn't a type of mana, so it's not something you can even have in your mana pool.
107.1c and 608.2d
"Any number" can be zero. Unless you're dividing or distributing something. That makes it awfully hard for a planeswalker's plus ability (which we like to always be activatable) to distribute counters—if you don't have any creatures, how could you distribute two counters among up to two target creatures? So we've shifted the rules and philosophy to allow you to distribute stuff among zero creatures, effectively not doing it at all, when an effect asks you to divide or distribute damage or counters or preventions. Dividing among zero doesn't allow you to divide by zero, which would make something in the universe crash. And yes, Magmatic Core is somewhat better.
Going back to how snow mana is weird, why do we call S "generic"? It can be paid with one mana of any type, sure, but most of the other rules about generic mana don't really apply quite right. So we'll stop calling S a generic mana symbol and just make other rules handle it being its own cool thing.
A new top-level rule! Woohoo! Tokens have languished way too long as a random sub-rule of permanents. Tokens are a major, common component of the game. Now they have their own home, with plenty of room to breathe, which I immediately stuffed up with new rules about the legendary token template and the new predefined token template. Stop breathing, tokens. It's creepy. Other than that, this is really just the old 110.5 moved down. And oh, boy, so many renumbered rules and references.
Enough people asked about copying a spell that had damage divided (can you re-divide it?) that I decided to add in a rule about it while looking at the other "divide among zero" change. This one isn't a rules change, just a helpful reminder that while changing targets, nothing more than the targets get to change.
If you offer up an Icehide Golem to your Patron of the Orochi (because, of course, you have an Arcane Adaptation or Conspiracy making all your creatures extra wiggly), what does that even do? It reduces the cost by one generic mana! This rule says so now.
Rule 119.9 (formerly known as rule 118.9 before the new 111 bumped it down) talks about life-gain triggers and how they work with multiple creatures with lifelink. Thanks to Angel of Vitality, now we need 119.10 that talks about life gain–replacement effects! Up until now, it didn't matter whether the replacement effect was just applying once or twice, but now it does, and this rule says it'll apply twice.
For basic lands, we have rules about how the mana abilities they get for their land type is an "intrinsic" ability. But for planeswalkers, we have some more nebulous words about how they get loyalty counters. I don't like nebulous words here, so I turned on a Giant Fan and blew the obscuring clouds away, and lo, planeswalkers have an intrinsic ability, too!
This rule could be read incorrectly to say "if you ever realize that you can't comply with any step, including one three steps down the line or one two steps ago, you've done goofed and your spell isn't legal to cast." I've tweaked it slightly to dodge that misreading. All that matters is whether you can comply with the step you're on now.
Remember when I said that after War of the Spark we could go back to ignoring this section for a while? Just kidding. We're back to add a rule about splice! I hope I haven't gotten this section's hopes up, because now I have no intention of coming back to it for years and years.
Can an Aura be attached to a player? Sure, says Bitterheart Witch, it's what she's all about. Of course, says Curse of Misfortunes, it's the funnest thing ever. Takklemaggot said something but I don't care because tl;dr. 701.3 is all about effects that instruct you to attach something to something else, but it weirded a couple people out when they noticed that it didn't allow for players, so I've updated the rule to make it more encompassing.
Sometimes the best way to word something so humans can understand it conflicts with the most logical wording. Winds of Abandon is a good example. It should cause each player to search their library once, not several times, but how do you word that well in a way that works with overload? How do you word it clearly at all, really? The solution we landed on is to make the rules support how it should work and not worry too much about whether you can guess the answer from reading the text; the difference only matters in edge cases, mostly involving Aven Mindcensor.
Protection from Pangolins and from Sponges is actually two abilities—which matters in like one situation ever. Similarly, this new rule explains that hexproof from blue and from black, showing up in Core Set 2020, is also two abilities. This doesn't matter in any situation I can think of offhand, but it's certainly how we want it to work, so in case it does matter somewhere, somehow, someday, now it'll be true.
702.21j and k
While looking over the rules for "any number" language where we don't want to allow zero, I hit banding. We really don't want you to be able to say "I just won't assign your combat damage lol," so I tweaked the words to get it off "any number."
Look at all those modes blissfully entwined. Previously, the entwine keyword was confined to "choose one" becoming "choose all," but Kaya's Guile got out there searching for higher goals, and now entwine can go sky high and let you "choose all" no matter how many modes you were supposed to choose.
I changed roughly everything about the words for splice and changed nothing whatsoever about how it works. I'm kind of impressed with the many-months-ago me who wrote them. These changes bring it from being a fuzzy weirdo to something well defined; it's a text-changing effect that adds rules text, copying the spell copies that choice and thus also gets the text, and you're adding text rather than effects.
If an Aura bestowed upon a Runeclaw Bear is phased out, and then the Bear is booped unto death, the Aura phases in unattached. It didn't "become unattached" since it was phased out when the attachment was broken, but we definitely want the bestow effect to end. This rule makes that happen.
Until Spark Double, there was no way to get a benefit out of having a Clone copy another Clone (which is itself not copying anything) over and over and over. If it gained an ability from doing so (like Progenitor Mimic), it overwrote that each time. Altered Ego was close, but the X doesn't track through cloning. But Spark Double would add a counter each time, and that was just silly. It's not that it's too powerful—it's just weird that it doesn't work like every other "Clone the Clone to copy itself ad nauseam" interaction. This new rule changes that so it does: copying something else wipes out the other bonuses of the first copy effect.