Comprehensive Rulebook Changes
What are the Comprehensive Rules?
Magic is complicated. No, really. When you have more than 12,000 interchangeable game pieces, you get some freaky interactions. The Comprehensive Rules cover everything the game has ever come up with, from basic game play structure, to every keyword ever, to entire pages dedicated to single bizarre cards (hello, Karn Liberated!). The Comprehensive Rules are, well, comprehensive… but they're also obtuse, unfriendly, and looooong. They're not intended to be a player resource—they're a judge resource, a rules guru resource, and a place to store definitive answers. In fact, I honestly recommend never reading them. For a much friendlier rulebook that is intended to be a player resource, check out the Rules Page and download the Basic Rulebook (2.1 MB PDF). It doesn't have sections about phasing or subgames… but you'll never miss them.
This rule explains who the owner and controller of a spell is. The sentence explaining who controlled a spell by default was tautological, saying essentially "its controller is its controller." I reworded it to be a little clearer, keeping in mind that copies of spells get onto the stack both by being created there (e.g. Twincast) and by being cast (e.g. Isochron Scepter).
These two rules explain, in part, that a player who can't gain or lose life can't exchange life totals with a player with a higher or lower life total, respectively. However, exchanging life totals is not the only exchange that could impact a life total, thanks to Tree of Redemption, so the two rules are being slightly broadened.
I'm proud to welcome Tamiyo and Tibalt to the family of planeswalker types.
303.4 & subrules
The rules previously spoke of the enchant keyword "restricting" what an Aura could be attached to. However, I believe this to be misleading. This paradigm starts with the assumption that Auras can be attached to anything and whittles down the set of objects they can be attached to based on enchant abilities. I believe a better paradigm is that Auras can't be attached to anything by default and the enchant abilities define that set of objects. The subrules in this section have been slightly reworded to emphasize this point.
This rule defines the conditions under which an effect is dependent on another. One of the conditions is that neither effect is from a characteristic-defining ability (CDA). However, this rule proved to be insufficient. Consider the case where a Sutured Ghoul has exiled a Maro. Sutured Ghoul's CDA needs to know the power and toughness of Maro, so it has to depend on Maro's CDA to get the correct value. (Keep in mind that Sutured Ghoul and Maro enter their respective zones simultaneously, so their relative timestamps could lead us astray.) So while it's true that a CDA and an ability that's not a CDA won't form a dependency, two CDAs could, so I'm adapting this rule for that situation.
In part of my ongoing project of improving the Aura rules (and this is far from the last change you'll see), I'm adding the following provision to this rule in the "Attach" section: If an effect tries to attach an object that isn't an Aura, Equipment, or Fortification to another object or player, the effect does nothing and the first object doesn't move.
It's a (section covering the rules for) miracle!
A new section covering soulbond. Note: if you read these rules in the Avacyn Restored FAQ, you might have noticed the rule numbers changed. I just made an error in the FAQ. I didn't get rid of banding or anything.
The rules for ending a subgame curiously left out what to do if you were also playing an Archenemy game, so this new rule covers it. But really? Shahrazad in Archenemy? Diabolical!
This is a new rule for multiplayer games for cards like Conjurer's Ban. Say I cast Conjurer's Ban and name Runeclaw Bear (because that sounds like winning strategy). Before my next turn, I leave the game, presumably because you have lots of Runeclaw Bears and want me gone. So, what happens to the effect of Conjurer's Ban? Having it end immediately felt really weird, especially considering effects of cards like Giant Growth wouldn't. Having it last indefinitely didn't feel right either. I decided that the most sensible thing was for the effect to end kinda, sorta close to when it was supposed to.
Miracle, soulbond entries added.