601.14a If a replacement effect tries to cause a spell or ability to affect an object or player outside its controller’s range of influence, that portion of the event does nothing.

Example: Alex plays Lava Axe (“Lava Axe deals 5 damage to target player”) targeting Rob. In response, Rob plays Captain’s Maneuver (“The next X damage that would be dealt to target creature or player this turn is dealt to another target creature or player instead.”) with X = 3, targeting Carissa. Carissa isn’t in Alex’s range of influence. When Lava Axe resolves, it deals only 2 damage to Rob and no damage to Carissa.

601.14b If a spell or ability creates an effect that prevents damage that would be dealt by a source, it can affect only sources within the spell or ability’s controller’s range of influence. If a spell or ability creates an effect that prevents damage that would be dealt to a creature or player, it can affect only creatures and players within the spell or ability’s controller’s range of influence. If a spell or ability creates an effect that prevents damage, but neither the source nor the would-be recipient of the damage is specified, it prevents damage only if both the source and recipient of that damage are within the spell or ability’s controller’s range of influence.

Example: Rob is within Alex’s range of influence, but Carissa is not. Alex controls an enchantment that says, “Prevent all damage that would be dealt by creatures.” Carissa attacks Rob with a creature. The creature deals combat damage to Rob.

Example: Rob is within Alex’s range of influence, but Carissa is not. Carissa plays Lightning Blast (“Lightning Blast deals 4 damage to target creature or player”) targeting Rob. In response, Alex plays Honorable Passage (“The next time a source of your choice would deal damage to target creature or player this turn, prevent that damage. If damage from a red source is prevented this way, Honorable Passage deals damage equal to the damage prevented this way to the source’s controller.”) targeting Rob. The damage to Rob is prevented, but Honorable Passage can’t deal damage to Carissa.

Example: Rob is within Alex’s range of influence, but Carissa is not. Carissa attacks Rob with a creature, and Rob blocks with a creature. Alex plays Holy Day (“Prevent all combat damage that would be dealt this turn.”) Carissa and Rob’s creatures deal combat damage to each other.

602.1. Some multiplayer games allow the active player to attack multiple other players. If this option is used, a player can also choose to attack only one player during a particular combat.

602.2. As the combat phase starts, the attacking player doesn’t choose an opponent to become the defending player. Instead, all the attacking player’s opponents are defending players during the combat phase.

602.2a Any rule, object, or effect that refers to a “defending player” refers to one specific defending player, not to all of the defending players. This will usually be the defending player that the creature with the ability is attacking; if there are multiple defending players that could be chosen, the controller of the ability chooses one.

602.3. As the attacking player declares each attacking creature, he or she chooses a defending player for it to attack. See rule 308, “Declare Attackers Step.”

602.3a Restrictions and requirements that don’t apply to attacking a specific player are evaluated based on the entire group of attacking creatures. Restrictions and requirements that apply to attacking a specific player apply only to creatures attacking that player. The entire group of attacking creatures must still be legal. See rule 500, “Legal Attacks and Blocks.”

Example: Rob attacks Alex with Grizzly Bears and attacks Carissa with a creature with mountainwalk. Whether the creature with mountainwalk is unblockable depends only on whether Carissa controls a Mountain.

602.3b Creatures in a band can’t attack different players. See rule 502.10, “Banding.”

602.4. If creatures are attacking more than one player, each defending player declares blockers in APNAP order as the declare blockers step begins. (See rule 103.4 and rule 309, “Declare Blockers Step.”) The first defending player declares all his or her blocks, then the second defending player, and so on.

602.4a A defending player can block only with creatures he or she controls. Those creatures can block only creatures attacking that player; they can’t block creatures attacking other players.

602.4b When determining whether a defending player’s blocks are legal, ignore any creatures attacking other players and any blocking creatures controlled by other players.

602.5. Combat damage is assigned in APNAP order. Other than that, the combat damage step proceeds just as in a two-player game. See rule 310, “Combat Damage Step.”

603.1. The Emperor variant always uses the deploy creatures option, and it can be used in other variants that allow players to compete in teams. Multiplayer formats in which players compete as individuals usually don’t use this option.

603.2. Each creature has the ability “{T}: Target teammate gains control of this creature. Play this ability only any time you could play a sorcery.”

604.1. Some multiplayer games use the optional attack left or attack right rules.

604.1a If the attack left option is used, a player can attack only an opponent seated immediately to his or her left. If a player’s nearest opponent to the left is more than one seat away, the player can’t attack.

604.1b If the attack right option is used, a player can attack only an opponent seated immediately to his or her right. If a player’s nearest opponent to the right is more than one seat away, the player can’t attack.

605.1 In Free-for-All multiplayer games, a group of players compete as individuals against each other.

605.2. Any multiplayer options used are determined before play begins. The Free-for-All variant uses the following default options.

605.2a The limited range of influence option usually isn’t used in Free-for-All games. If it is, each player has the same range of influence, which is determined before play begins. See rule 601, “Limited Range of Influence Option.”

605.2b Exactly one of the attack left, attack right, and attack multiple players options must be used. See rule 604, “Attack Left and Attack Right Options,” and rule 602, “Attack Multiple Players Option.”

605.2c The deploy creatures option isn’t used in the Free-for-All variant.