Shared turns

From the glossary of the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

Shared Team Turns Option

An option that may be used in certain multiplayer variants, such as Two-Headed Giant and Archenemy. See rule 805, “Shared Team Turns Option.”

From the Comprehensive Rules (June 7, 2024—Modern Horizons 3)

• 805. Shared Team Turns Option
  • 805.1. Some multiplayer games between teams use the shared team turns option. It’s always used in the Two-Headed Giant variant (see rule 810) and the Archenemy casual variant (see rule 904). It can be used only if the members of each team are sitting in adjacent seats.
  • 805.2. Within each team, the player seated in the rightmost seat from that team’s perspective is the primary player. If the players on a team can’t agree on a choice, such as which creatures attack or what order triggered abilities are put on the stack, the primary player makes that choice.
  • 805.3. The methods described in rule 103.1 are used to determine which team will take the first turn. The team determined this way is the starting team.
    • 805.3a The process for handling mulligans is altered accordingly. First, each player on the starting team, in whatever order that team likes, declares whether that player will take a mulligan. Then the players on each other team in turn order do the same. Teammates may consult while making their decisions. Then all mulligans are taken at the same time. Teammates may consult while choosing which cards, if any, to put on the bottom of their library. A player may take a mulligan even after a teammate has decided to keep their opening hand. See rule 103.5.
    • 805.3b The process for handling cards that allow a player to begin the game with them on the battlefield is altered accordingly. First, each player on the starting team, in whatever order that team likes, may put any or all such cards onto the battlefield from that player’s opening hand. Teammates may consult while making their decisions. Then each player on each other team in turn order does the same.
  • 805.4. Each team takes turns rather than each player.
    • 805.4a The team whose turn it is is the active team. Each other team is a nonactive team.
    • 805.4b Each player on a team draws a card during that team’s draw step.
    • 805.4c Each player on a team may play a land during each of that team’s turns.
    • 805.4d An ability that triggers at the beginning of a step or phase may trigger multiple times if it triggers at the beginning of “each player’s” or “each opponent’s” step or phase. These abilities trigger once for each appropriate player if the ability’s trigger condition, effect, or intervening “if” clause refers to “that player,” “that opponent,” or similar.
  • 805.5. Teams have priority, not individual players.
    • 805.5a A player may cast a spell, activate an ability, or take a special action when their team has priority.
    • 805.5b If a team has priority and no player on that team wishes to do anything, that team passes. If all teams pass in succession (that is, if all teams pass without any player taking any actions in between passing), the top object on the stack resolves, then the active team receives priority. If the stack is empty when all teams pass in succession, the phase or step ends and the next one begins.
  • 805.6. The Active Player, Nonactive Player order rule (see rule 101.4) is modified if the shared team turns option is used. If multiple teams would make choices and/or take actions at the same time, first the active team makes any choices required, then each nonactive team in turn order makes any choices required. If multiple players would make choices and/or take actions at the same time, first each player on the active team makes any choices required in whatever order they like, then the players on each nonactive team in turn order do the same. Once all choices have been made, the actions happen simultaneously.
    • 805.6a If more than one player is instructed to draw cards in a game that’s using the shared team turns option, first each player on the active team, in whatever order that team likes, performs that player’s draws, then each player on each nonactive team in turn order does the same.
  • 805.7. If multiple triggered abilities have triggered since the last time a team received priority, the members of the active team put all triggered abilities any of them controls on the stack in any order they choose, then the members of each nonactive team in turn order do the same.
  • 805.8. If an effect gives a player an extra turn or adds a phase or step to that player’s turn, that player’s team takes the extra turn, phase, or step. If an effect causes a player to skip a step, phase, or turn, that player’s team does so. If a single effect causes more than one player on the same team to add or skip the same step, phase, or turn, that team adds or skips only that step, phase, or turn. If an effect causes a player to control another player, the first player controls the affected player’s team.
  • 805.9. Any ability that refers to the “active player” refers to one specific active player, not to all of the active players. The ability’s controller chooses which one the ability refers to at the time its effect is applied.
  • 805.10. The shared team turns option uses different combat rules than other multiplayer options.
    • 805.10a Each team’s creatures attack the other team as a group. During the combat phase, the active team is the attacking team and each player on the active team is an attacking player. Likewise, the nonactive team is the defending team and each player on the nonactive team is a defending player.
    • 805.10b As the declare attackers step begins, the active team declares attackers. For each attacking creature, the attacking team announces which defending player, planeswalker, or battle that creature is attacking. The active team has one combined attack, and that set of attacking creatures must be legal as a whole. See rule 508.1.
    • 805.10c Any rule, object, or effect that refers to an “attacking player” refers to one specific attacking player, not to all attacking players. If an ability of a blocking creature refers to an attacking player, or a spell or ability refers to both a blocking creature and an attacking player, then unless otherwise specified, the attacking player it’s referring to is the player who controls the attacking creature that blocking creature is blocking. If a spell or ability could apply to multiple blocking creatures, the appropriate attacking player is individually determined for each of those blocking creatures. If there are multiple attacking players that could be chosen, the controller of the spell or ability chooses one.
    • 805.10d As the declare blockers step begins, the defending team declares blockers. Creatures controlled by the defending players can block creatures attacking any player on the defending team, attacking a planeswalker controlled by one of those players, or a battle protected by one of those players. The defending team has one combined block, and that set of blocking creatures must be legal as a whole. See rule 509.1.
    • 805.10e Any rule, object, or effect that refers to a “defending player” refers to one specific defending player, not to all of the defending players. If an ability of an attacking creature refers to a defending player, or a spell or ability refers to both an attacking creature and a defending player, then unless otherwise specified, the defending player it’s referring to is the player that creature is attacking, the controller of the planeswalker that creature is attacking, or the protector of the battle that creature is attacking. If that creature is no longer attacking, the defending player it’s referring to is the player that creature was attacking before it was removed from combat, the controller of the planeswalker that creature was attacking before it was removed from combat, or the protector of the battle that creature was attacking before it was removed from combat. If a spell or ability could apply to multiple attacking creatures, the appropriate defending player is individually determined for each of those attacking creatures. If there are multiple defending players that could be chosen, the controller of the spell or ability chooses one.
    • 805.10f Once blockers have been declared, for each attacking creature that’s become blocked by multiple creatures, the active team announces the damage assignment order among the blocking creatures. Then, for each creature that’s blocking multiple creatures, the defending team announces the damage assignment order among the attacking creatures.
    • 805.10g As the combat damage step begins, the active team announces how each attacking creature will assign its combat damage. Then the defending team announces how each blocking creature will assign its combat damage. See rule 510.1.