Comprehensive Rules/Changes

The comprehensive rules have changed many times throughout the years. Those changes tend to correspond with the release of a new set. While many of the changes are changes in wording or numbering, others fundamentally change gameplay. For example, with the release of Battle for Zendikar, the rules were updated so that after mulligans were taken, each player with fewer cards in hand than the starting value was allowed to Scry 1. A full list of changes can be found at https://vensersjournal.com/archives (starting with Rivals of Ixalan) and http://www.yawgatog.com/resources/rules-changes/ (up to Ixalan).

Dominaria

 * New Keyword: Double.
 * New Keyword Variants: Hexproof from [quality] and Equip [quality] creature.
 * New Enchantment Type: Saga.
 * New Planeswalker Type: Jaya.
 * New Game Term: Historic.
 * Chapter symbols added that represent chapters as a keyword ability, similar to the Level symbol from Rise of the Eldrazi.
 * The Legendary supertype expanded. Legendary sorcery spells can only be cast if the player controls a legendary creature or planeswalker.
 * The order of three or more color mana symbols standardized. Wedges have the shared enemy color in the center.
 * Cards that referenced their own name while casting themself received errata to "this spell" instead of repeating the card name.
 * The planeswalker redirection rule was removed and cards referencing damaging players received errata specifying damaging players or planeswalkers.
 * The template for pronouns changed from "He or She" and "Him or Her" to singular "They" and "Them".
 * The template for "Add mana to a mana pool" shortened to "Add {mana}".

Rivals of Ixalan

 * New Keywords: Ascend.
 * New Ability Words:
 * New Player Designation: City's Blessing.
 * New Planeswalker Type: Angrath.

Unstable

 * Unstable did not introduce any new black border rules. Instead, Mark Rosewater wrote an FAQ for the Unstable silver-border rules changes, and many Unglued and Unhinged cards received oracle text updates.
 * Assemble added to the glossary in the comprehensive rules, pointing to Mark Rosewater's silver-border FAQ.

Ixalan

 * New Keywords: Explore.
 * New Ability Word: Enrage.
 * New Creature Types: Trilobite and Dinosaur.
 * New Artifact Type: Treasure.
 * New Planeswalker Type: Huatli.
 * The planeswalker uniqueness rule has been removed and all planeswalkers have received errata to have the Legendary supertype.

Commander 2017

 * New Ability Word: Eminence.
 * Tokens no longer cease to exist when phased out.

Hour of Devastation

 * New Keyword: Eternalize and Afflict.
 * New Planeswalker Type: Samut.

Amonkhet

 * New Keywords: Embalm, Exert, and Aftermath.
 * New Creature Type: Jackal.
 * New Enchantment Type: Cartouche.
 * Characteristics of split cards changed. While not on the stack, the card's characteristics are a combination of both halves. A split card with instant and sorcery is an Instant and a Sorcery when not on a stack, and it's converted mana cost is the sum of both halves.
 * With Heart-Pierce Manticore, reflexive triggered abilities are introduced.

Aether Revolt

 * New Keywords: Improvise.
 * New Ability Words: Revolt.

Commander 2016

 * New Keywords: Partner, Undaunted.

Kaladesh

 * New Mechanic: Energy.
 * New Keywords: Create,
 * New Ability Words:
 * New Artifact Type: Vehicle.
 * New Planeswalker Types: Dovin and Saheeli.
 * New Creature Types: Aetherborn, Monkey, Pilot, and Servo.
 * The Æ ligature replaced with "Ae".

Conspiracy: Take the Crown

 * New Player Designation: Monarch.
 * New Keywords: Goad and Melee.
 * New Ability Word: Council's Dilemma.
 * New Planeswalker Type: Kaya.

Eldritch Moon

 * New Keywords: Meld, Emerge, Escalate.

Shadows Over Innistrad

 * New Keywords: Investigate and Skulk.
 * New Ability Word: Delirium.
 * If an object gains an ability, the value of within that ability is the value defined by that ability, or 0 if that ability doesn't define a value of.
 * The converted mana cost of the back side of a Double-faced card is the same as its front side. It used to be 0.
 * If a spell or ability instructs a player to transform a permanent, and the face that permanent would transform into is represented by an instant or sorcery card face, nothing happens.
 * If a spell or ability attempts to transform a permanent, but that permanent has transformed since the spell or ability was put on the stack, the permanent does not transform.
 * If a player is instructed to put a card that isn't a double-faced card onto the battlefield transformed, that card stays in its current zone.

Oath of the Gatewatch

 * New Keywords: Support and Surge.


 * Added (represented by the letter 'C') as a symbol for colorless mana. Older cards that read "Add  to your mana pool" received errata to read "Add  to your mana pool". This is solely a templating change, not a functional one.  in a mana cost must be paid with colorless mana. Generic mana costs (,,,etc) can still be paid with any color of mana.
 * Effects that would add mana represented by a generic symbol (,,, etc) to a mana pool add that much colorless mana.
 * Removed alternate mulligan rule for Commander. Commander now uses normal mulligan rules for two-player or multiplayer games.
 * Mana of any color can be added to your mana pool. Previously mana not in your commander's color identity was converted to colorless mana.

Commander 2015

 * New Keyword: Myriad.
 * Retained the Partial Paris Mulligan in Commander format.

Battle for Zendikar

 * New keywords: Awaken, Devoid, and Ingest.
 * New ability words: Rally and Convoke.
 * Vancouver Mulligan — After all players have kept an opening hand, each player in turn order whose hand contains fewer cards than that player's starting hand size may look at the top card of his or her library. If a player does, that player may put that card on the bottom of his or her library.
 * Face-down cards in exile should be kept in separate piles based on when they were exiled and how they were exiled. If a player is instructed to choose an exiled card, the player may choose a specific face-down card only if the player is allowed to look at that card. Otherwise, he or she may choose a pile of face-down exiled cards, and then a card is chosen at random from within that pile. If choosing such a card is part of casting a spell or activating an ability, the chosen card isn't revealed until after that cost is fully paid.
 * If a player would Scry 0 that player does not scry.

Magic Origins

 * New ability word: Spell Mastery.
 * New keywords: Menace and Renown.
 * Choices for spells are made before legality is checked. If you cannot cast creature spells, you can still cast a spell with Bestow as an aura.
 * Permanents get a new timestamp when they turn face-up, turn face-down, or transform.
 * If you would shuffle a card(s) into your library, but no cards are added to your library (for example, due to a replacement effect) you still shuffle the library.
 * The Chaos symbol,, is now represented by the word 'CHAOS' instead of 'C'.


 * If your commander would be exiled or go to your hand, library or graveyard, you may chose to have it go to the command zone instead. (Previously this was only the case for exile and graveyard)

Dragons of Tarkir

 * New ability word: Formidable.
 * New keywords: Exploit and Megamorph.
 * New Planeswalker Type: Narset.

Fate Reforged

 * New ability word: Lieutenant.
 * New keywords: Bolster, Manifest, and Dash.
 * New Planeswalker Type: Ugin.
 * If you are instructed to pay the mana cost of a card with in its cost,  is  unless the card is a spell on the stack, in which case it  is whatever was chosen for it.
 * Some permanents make you choose between multiple abilities. Each ability is associated with an anchor word. "[Anchor word] — [ability]" means "As long as [anchor word] was chosen as this permanent entered the battlefield, this permanent has [ability]."
 * Double-faced cards (DFC) can now be cast face-down. Face-down is not the same as transformed, a face-down DFC has the characteristics defined by whatever caused them to be face-down and cannot transform. When it is turned face-up its front face is showing. DFC on the battlefield cannot be turned face-down.

Khans of Tarkir

 * New ability words: Ferocious and Raid.
 * New Keywords: Outlast and Prowess.

Magic 2015

 * If searching a zone is replaced with searching a portion of that zone, any abilities that trigger on searching that zone still trigger.

Conspiracy

 * Defined the Conspiracy Draft format.
 * New card type: Conspiracy.
 * New special action: turning a face-down conspiracy card face-up.
 * New Keywords: Vote, Dethrone, Hidden agenda.
 * New Planeswalker Type: Dack.

Journey into Nyx

 * New Ability Words: Constellation and Strive.

Born of the Gods

 * New Ability Word: Inspired.
 * New Keyword: Tribute.
 * New Planeswalker Type: Kiora.
 * Devotion to [color 1] and [color 2] is equal to the number of mana symbols among the mana costs of permanents that player controls that are [color 1], [color 2], or both colors. Hybrid Symbols are only counted once, even if they have both colors.
 * Auras and equipment that move from one card to another unattach from the first card, but never become unattached.
 * Main-game counters on players are considered not to exist during a subgame. Subgame counters cease to exist at the end of the subgame.
 * Schemes are now set into play one at a time.
 * Casting a commander from the command zone also requires an additional for each time the casting player has cast that commander this game. This was changed because Daxos of Meletis could allow a player to cast a different player's commander from the command zone.

Commander 2013

 * New Ability Word: Tempting offer.
 * Protection from [Player] means protection from each object controlled by that player and each object owned by that player that is not controlled any player.

Theros

 * New Keywords: Monstrosity and Bestow.
 * Devotion to [color] is equal to the number of mana symbols of that color among the mana costs of permanents that player controls.
 * New Planeswalker Type: Xenagos.
 * "Equipped", "Fortified", and "Enchanted" are all now synonyms for "attached". Permanents with abilities that refer to the "Equipped creature", "Fortified land", and "Enchanted  [object or player]" simply refer to the the object or player the permanent is attached to, as long as the object or player is of the correct type. "For example, there was a weird combo with Myr Welder exiling Demonspine Whip and Transmogrifying Licid. The Welder could now become an Aura and attach to a creature." Under the new rules, the Welder's ability referring to the "Equipped Creature" is synonymous with "Enchanted Creature".

Magic 2014

 * New Keyword: Indestructible. (indestructible was previously a descriptor)
 * Convoke used to reduce the cost of casting a spell. Now it replaces paying mana. This prevents you from "over-convoking" or tapping more creatures than required.
 * Delve used to reduce the cost of casting a spell. Now it replaces paying mana. This prevents you from "over-delving" or exiling more cards than required.
 * Unblockable was removed as a keyword. Cards now say "can't be blocked".
 * Sideboards for constructed play may now contain up to 15 cards. Players are no longer required to exchange cards one-for-one between their sideboard and main deck.
 * Expansion symbol is no longer a characteristic of cards. Cards that previously cared about this have received errata to say "cards originally printed in [set]".
 * You can no longer be required to cast a spell with a mandatory additional cost that includes actions involving cards with a stated quality in a hidden zone if able. For example, if a card says "as an additional cost to cast this card, reveal a creature from your hand" you can choose not to pay the cost and not cast the spell.
 * If an effect would put a non-aura card onto the battlefield attached to a creature, it enters unattached.
 * When a player attempts to play a land, compare the number of lands that player has played this turn to the number he or she is allowed to play this turn. If the later is less than or equal to the former, that player may not play the land.
 * New Planeswalker uniqueness rule, if a player controls two or more Planeswalkers that share a planeswalker type, that player chooses one and the rest go to their owner's graveyards.
 * New legend rule, if a player controls two or more Legendary permanents that share a name, that player chooses one and the rest go to their owner's graveyards.
 * If an ability refers to the card exiled by an effect, but multiple cards were exiled (because the effect was copied, for example), it refers to all of those cards. If it checks the characteristics of the card, it sums that characteristic for all of them. If it would do something to the card, it does it to all of them.
 * If a effect causes a card to change zone "until" a future point, it immediately creates a second event to move the card back. If the specified event has already occurred when the initial one-shot effect would cause the object to change zones, the object doesn't move.

Dragon's Maze

 * New Keyword: Fuse.
 * New Planeswalker Type: Ral.
 * When instructed to "name a card", you may only name one half of a split card. Previously you were required to name both halves.
 * Abilities that trigger when a card "attacks and isn't blocked" trigger when blockers are declared (even if the declaration is "no blockers").
 * If an effect replaced searching a zone with searching a portion of a zone, that is still considered searching that zone.
 * A creature that gains more than one +1/+1 counter due to Evolve still only "evolves" once.

Gatecrash

 * New Ability Words: Battalion and Bloodrush.
 * New Keywords: Cipher, Evolve, and Extort.
 * If an ability refers to an undefined choice, that part of the ability won't do anything.
 * If mana is restricted based on an undefined choice, that mana can't be spent.
 * If a replacement effect that modifies how a permanent enters the battlefield requires a choice, that choice is made before the permanent changes zones.
 * If a spell states that it may be cast only "after [a player's] upkeep step," and the turn has multiple upkeep steps, that spell may be cast any time after the first upkeep step ends.
 * If a continuous effect has parts that modify the characteristics of cards and parts that affect cards without modifying their characteristics, the set of cards affected is determined separately for each part of the effect.
 * If a player leaves the game, abilities from Phenomena that they control stay on the stack, and are now controlled by the new planar controller.

Return to Ravnica

 * New Planeswalker type: Vraska.
 * New Keywords: Detain, Populate, Overload, Scavenge, and Unleash.
 * If a player would search a zone for cards of an undefined quality, that player may search but cannot find any cards.
 * If an ability triggers when an object "transforms into" an object with a specific name, it only triggers if that object had a different name, transforms, and now has the specified name.

Magic 2013

 * The same object can't be chosen to change zones more than once when applying replacement effects that modify how a single permanent enters the battlefield.

Planechase 2012

 * New Card type: Phenomenon.
 * Each phenomenon card has a triggered ability that triggers when you encounter it. "When you encounter [this phenomenon]" means "When you move this card off a planar deck and turn it face up."
 * If a phenomenon card is face up in the command zone, and it isn't the source of a triggered ability that has triggered but not yet left the stack, the planar controller planeswalks the next time a player would receive priority.
 * No more than two cards in a planar deck can be phenomenon cards. If there is a shared planar deck it can't contain more phenomenon cards than twice the number of players in the game.