From the top!
This rule talks about numbers and how Magic mostly uses only positive numbers and zero, although certain values like power and toughness can go negative. The last sentence used to say that calculations yielding negative numbers use zero for their effects unless that effect is affecting a player's life total or a creature's power and/or toughness. But Scourge of the Skyclaves (not to mention Roiling Horror before it) has an ability that applies in all zones. So, Scourge of the Skyclaves will sometimes have a negative power and toughness in your graveyard, where it's not a creature but a creature card. Thus, we expanded that last sentence a hair.
We inserted a rule in the X section to clarify who exactly is going to give it to you. Actually, it's a rule to cover cards like Zaxara, the Exemplary, which uses X in a way such that its value is derived from another object. Subsequent rules in this section were renumbered.
A new rule at the end of the token section to talk about tokens that enter the battlefield as a result of a copy of a permanent spell resolving, a new thing as of Zendikar Rising. Those tokens are not "created," so they won't interact with cards that care about creating a token. Sorry, Doubling Season fans.
A new rule in the damage section to explain how abilities like the second ability of Anowon, the Ruin Thief work. If a trigger condition specified damage dealt by a specific source or sources, later instances of "that damage" refer only to the damage dealt by those sources and not to other damage dealt at the same time. So Anowon mills cards equal to the combat damage dealt by the Rogues, not by your non-Rogues.
This rule in the expansion symbol section dealt with cards that affect a particular set, like Golgothian Sylex or City in a Bottle. It used to point you at rule 700.8 for the detailed lists. We've moved those lists up to this rule for convenience. The 700 section is really for rules that don't have a convenient home elsewhere, and this one fit here.
A small tweak to the characteristic-defining ability rule to allow for characteristic-defining abilities that add to a card's printed characteristics rather than overriding them. This is for the party-helper cards in Zendikar Rising like Tajuru Paragon.
Copies of permanent spells return for another appearance, this time in the section that details how resolving permanent spells works. The resulting token stops being a copy of a spell and becomes a token, which still isn't "created." Sorry, Anointed Procession fans.
This used to be the rule talking about cards that affect a particular set. Since that rule moved out, we've decided to throw a party. Specifically, the rules for defining party, the Zendikar Rising mechanic. These rules define party, full party, and tell you to calculate the number of creatures in your party in a variety of situations.
A very minor tweak of the meld rules to correct something I noticed in passing: The rule said if an effect instructs a player to meld cards that can't be melded, they stay in their current zone. But really, that should be objects and not cards, as one of the key situations this rule guards against is token copies of meld cards trying to meld.
Another mention of copies of permanent spells, this time in the rule that talks about copying a spell or ability. Still no "creating." Sorry, fans of Akim, the Soaring Wind.
This is the section on double-faced cards. A lot of changes here. To summarize, there are now two kinds of double-faced cards: transforming double-faced cards and the new modal double-faced cards. They have a lot in common, but each has a defining trait of sorts: Transforming double-faced cards are the only cards that can transform on the battlefield or enter the battlefield transformed. Modal double-faced cards are the only cards that be played or cast with either face up.
Other rules that deal with double-faced cards were changed accordingly. Some rules that applied to all double-faced cards now apply only to transforming double-faced cards, and some rules were updated to explain how to handle both kinds. Here's a quick rundown:
Some tweaks to these rules that explain how the converted mana cost of a double-faced permanent is calculated. It used to be that a double-faced permanent with its back face up used the mana cost of the front face to determine its converted mana cost. Now that's true of transforming double-faced permanents only. The converted mana cost of a modal double-faced permanent is determined using the mana cost of the face that's up.
This rule says that an ability printed on one face of a double-faced card can be linked to an ability printed on the other face. That's true of transforming double-faced cards only now.
This rule gives a new timestamp to a transforming double-faced card each time it transforms.
This rule is for the transform keyword action. Only permanents represented by transforming double-faced cards can transform.
If a merged permanent contains any transforming double-faced cards, transforming that permanent will cause each of those double-faced cards to turn to their other face. If a merged permanent contains modal double-faced cards and no transforming ones, transforming that permanent has no effect.
This is the section on what used to be called checklist cards, game supplements for playing with double-faced cards. They substitute for a double-faced card in hidden zones. They can be used in place of (or in addition to) opaque sleeves to make sure your double-faced cards are indistinguishable from other cards in your deck. Zendikar Rising has its own twist on them for modal double-faced cards. "Checklist" was an increasingly inaccurate way to refer to them, and it's been that way since Nicol Bolas, the Ravager in Core Set 2019. So, we're giving them a slightly more accurate name: substitute cards. Details on when they can be used and how to use them haven't changed.
New entries: Full Party, Modal-Double Faced Cards, Party, and Transforming Double-Faced Cards
Checklist Card becomes Substitute Card.