This is completely out of curiosity, so don't waste a lot of time on this one.

I found an obscure rules interaction and wonder if this is even covered in the rules. You may skip down to the rule in question right away, otherwise here is the whole chain:

703.4f Immediately after the beginning of combat step begins, if the game being played is a multiplayer game in which the active player’s opponents don’t all automatically become defending players, the active player chooses one of their opponents. That player becomes the defending player. See rule 507.1.

507.1 First, if the game being played is a multiplayer game in which the active player’s opponents don’t all automatically become defending players, the active player chooses one of their opponents. That player becomes the defending player. This turn-based action doesn’t use the stack. (See rule 506.2.)

506.2a During the combat phase of a multiplayer game, there may be one or more defending players, depending on the variant being played and the options chosen for it. Unless all the attacking player’s opponents automatically become defending players during the combat phase, the attacking player chooses one of their opponents as a turn-based action during the beginning of combat step. (Note that the choice may be dictated by the variant being played or the options chosen for it.) That player becomes the defending player. See rule 802, “Attack Multiple Players Option,” rule 803, “Attack Left and Attack Right Options,” and rule 809, “Emperor Variant.”

802.1 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.



Here it becomes interesting!

802.2 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.

This does not make things bananas by itself, thanks to 802.2a. Mountainwalk is used as an example. All is good. As long as we are passed declare attackers…

802.2a Any rule, object, or effect that refers to a “defending player” refers to one specific defending player, not to all of the defending players. 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, or the controller of the planeswalker 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 or the controller of the planeswalker 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.


Of course I got curious to find interaction where the rule stating that everyone is a defending player, regardless if that player is attacked or not, makes a difference. Context of these questions is Commander. I found this card:

Arcum's Sleigh

Obviously you need to activate this prior attacking. Does this mean that as long as any opponent has a snow covered land I can activate this?

Does it also mean I can play Yare before declaring attackers? Or even after attackers, on a creature not controlled by a player not being attacked (nor a planeswalker that player controls)?

Is there any other cases where the rule that everyone is defending player makes a difference?

Edited Olle Liljefeldt (Sept. 5, 2019 03:40:51 PM)