This rule referred to making choices for how to pay costs during resolution by saying to choose while paying. To better reflect reality (and to work with our best buddy, K'rrik), it's been updated slightly to clarify that you choose how to pay the cost immediately before doing so.
When this rule refers to "gaining" an ability, it uses "gain" in the English language sense of "it didn't have an ability and now it does somehow, what has science done?" and not "literally uses the word 'gain.'" I've changed the rule to explicitly say that.
Chamber Sentry got 107.3j to clarify an object with X in its cost and in an unrelated activated ability. Now Gadwick, the Wizened gets a new 107.3k rule to clarify that its triggered ability looks at the value X that comes from the spell it was, not the permanent it is.
110.2b and 800.4c
If I steal your creature then lose the game, you get it back since you're its default controller. If I steal your spell then lose the game before it resolves, you get it back since you're its default controller. But if I steal your spell, and it becomes a permanent, then I lose the game, you didn't used to get it back. That's changed to line up with other effects that change an object's controller, though, if I take something from you that you never controlled (with Bribery, for example), it still gets exiled if I lose the game.
A kind reader pointed out that this rule was not only incomplete and slightly confusing, its example had the wrong Oracle text for Prodigal Pyromancer! I've rewritten it to be more accurate and actual, but it's not a functional change.
All of the rules for paying multiple-choice costs are consolidated here, including beefing up the rules for hybrid to make it clearer how K'rrik, Son of Yawgmoth works with hybrids. K'rrik totally loves hybrids, especially when they're at least part Negator.
I was tempted to jump numbering and make this 122.12 because it's the Midnight Clock rule. It says that "the twelfth counter" means "the number of counters goes to twelve!" and not to look at the entire history of the Clock to see how many counters were ever put on it. If you put eleven counters on it, then remove them all, the next counter is the twelfth counter from a certain English-language standpoint, but it's the first as far as the rules care.
You can't necessarily choose your own Adventure, but you can choose the alternative name of an Adventure if you're asked to choose a card name.
If an object is said to become a certain list of types, these overwrite any other types it has. Except "artifact creature." This exception's been floating around for all of the game's history, and we're not quite ready to remove it yet, but we're making one little modification to it: if it sets the object's creature types in the process, the object keeps all of its card types but loses its other creature types.
205.3g, j, k, and m
The subtypes! So many new subtypes! We've got Oko, Serra, and Wrenn joining the list of planeswalkers. We've got Mouse, Noble, Peasant, Warlock, and Sculpture joining the list of creature types. Even the artifact and spell types get in on the fun with Food and Adventure. Lands and enchantments don't get to join the festivities, much to New Mexico's chagrin.
For details on what changed, see "Noblesse Oblige" in the Oracle changes section.
Here's where we list ability words. An ability word appears in italics and has no rules meaning, but we list them anyway. Welcome to the club, adamant.
Throne of Eldraine features a change to the information below the text box. Shocking, I know. No longer do we have card 1408/249—for anything over the collector number max (which means it's an alternate version or from an ancillary product), we just omit the total.
The rules for Equipment always referred to Equipment attached to objects. After all, how would you attach an Equipment to a player? Liquimetal Coating, Brudiclad, and a token copy of a Curse will do it. Or Liquimetal Coating, a Curse, and Masterful Replication. Or Liquimetal Coating, a Curse, and Saheeli, Sublime Artificer. Basically, Liquimetal Coating. The rules for Equipment have been updated to clarify that an Equipment attached to anything, not just an object, falls off if that thing isn't a creature.
Speaking of Auras doing weird things, here are the rules for turning Auras face up. Aura, singular, really. It only applies to Gift of Doom. For now.
If you do something to specifically modify a permanent spell on the stack, that modification applies to the permanent the spell becomes. But this rule didn't need to include changing its controller, since previously the spell's controller would just become the permanent's default controller. Now it does count control-changing effects.
I added a clause here to make something clearer: if you cast a permanent spell with an adamant ability, and I use Desertion to counter it, the card that I put onto the battlefield isn't the resolving spell, so I don't get the bonus.
Tahngarth, First Mate is also the first card to say that a creature simply becomes an attacking creature. Here's the rule for that!
We had some contradictory rulings going on about split cards versus morph and when you look at what sets of characteristics. Adventures gave us the reason to shore up these rules. This isn't a change for morph, but it does change some answers for split cards: if you're allowed to cast a spell with a certain mana cost or color, look only at the half you're casting. Kari Zev's Expertise will allow you to cast Beck (but not Call).
But stop right there before you get too excited—you can't cascade into Beck // Call with Shardless Agent, since cascade finds a card with a certain converted mana cost and then says that you can cast the card you found. Beck // Call's converted mana cost is 8, and 8 > 3, so you're still out of luck with cascade.
The old 601.3 rule started off by talking about whether it was legal to begin casting, and then all of its subrules went into details. But then the main rule continued on talking about what if it became illegal! I broke that out into its own rule and added clarity that becoming illegal after the proposal is done doesn't matter.
Thanks to the Kenrith, reflexive triggers have an update to account for a first in Magic: triggering off of multiple events that occurred. This works for reflexive triggers pretty cleanly since they have a very narrow window to look at, but don't expect it to spread to normal triggers.
With adamant coming out, we decided that it was well worth adding a reminder rule to point at that clearly states how mana washing ("You may spend mana as though it were mana of any color/type") works. You don't choose a color to spend mana as; you're simply allowed to spend it to pay for a cost.
The rules for goad gain two new subrules! One for a static "is goaded" effect, and one to establish that being goaded multiple times by one player isn't extra goady.
There's a new rule here to codify something that we've ruled for nearly two decades: if something runs through a laundry list of abilities to grant and hits one with parameters (like protection, landwalk, or hexproof), it grants that keyword each time for each appropriate parameter. It's not a change to anything you've seen, just putting it in the rules for support.
Similarly, this rule establishes for a fact that looking for a card "with cycling" can find something with cycling 1, cycling 2, etc. After all, nothing has "cycling," so this should be obvious! It's less obvious when we need to say "with hexproof."
We have a rule for gaining protection from "all" of something, but "each" is similar yet slightly different. It's functionally the same, just linguistically separate. Yay for language!
This rule spells out that Wall of Stolen Identity only gets to trigger if its copy effect is the last one to copy the creature. This stops any sort of awful loops where Wall of Stolen Identity can tap down multiple creatures.
Here's another big fun question for adamant: copying spells! Rather than write a new rule, I just added this as an example here. None of the new cards with adamant were as clean and simple as Dawnglow Infusion, so I just used that old card instead of a new one, but between you and me, we're really talking about adamant cards here.
And here's where adventurer cards go! They're not technically called Adventure cards, but I won't yell at you if you leave off that r on the end.
This whole section on ending the turn is rewritten to handle ending phases, too. I wonder what else we can end?
Magic's second Sponge, Thought Sponge, asked us to add this rule to make it clearer how it works with players who lose the game. It was just too adorable to deny.
Here's where we define how seating order works—basically, any way you like. It's reinforcing that if someone's showing Pramikon, Sky Rampart, your group is fine if you work out who should sit where, and you're also fine if you arrange yourselves randomly. There's no wrong way. No, don't sit on top of each other. What have you done?