How many Champions in "sideboard" for commander?

[darrenhabib]

Going to be hard one to answer as its up to RC to define the rule.

You can reveal one card as your "champion" at start of game, and deck must have the relevant deck constructing requirements.

But in theory can you put multiple champions into your sideboard, and they won't be revealed as your champion, therefore you don't need the deck building requirements?
You can obviously do this in sideboarded constructed formats.

But can you do this for commander so that you can finally use cards like Glittering Wish and Living Wish to get Keruga, the Macrosage, Umori, The Collector, Gyruda, Doom of Depths from the "sideboard".

That is specifically can I have all 3 of these creatures in the sideboard?

[peteroupc]

Cards with a companion ability can be chosen from "outside the game" in the same way as though they didn't have any companion abilities. A player can choose no more than one card with a companion ability as a companion (not: champion), even if more than one card with a companion ability is in that player's sideboard. Companion abilities care about the composition of a player's starting deck, not that player's sideboard.

Note that nothing in the rules for the Commander variant (under C.R. 903) changes what "outside the game" means. In general, in a game other than in a sanctioned tournament (compare with M.T.R. 3.15), a card "you own from outside the game" is a card you own that isn't in any of the game's zones, including a card in a sideboard (C.R. 400.11, 400.11a).

In unsanctioned casual games in general, the players in the game can agree on modifications to the comprehensive rules (that is, "house rules") that address various game details, examples of which are—

• each player's starting life total,
• whether players can have sideboards,
• the meaning of "outside the game", and
• the number of poison counters needed for a player to lose the game as a state-based action.

For example, although a card "outside the game", under the comprehensive rules, means a card that's not in any of the game's zones, including a card in a sideboard (C.R. 400.11, 400.11a), and nothing in the rules for the Commander variant (under C.R. 903) changes this, the players in an unsanctioned casual game can agree to limit the term "outside the game" to meaning only cards in sideboards, as the Magic: The Gathering Tournament Rules does for sanctioned tournaments (M.T.R. 3.15).

EDIT (Apr. 16): Edited because the update bulletin was released.
EDIT (Apr. 17): Edited to conform to rule update with Ikoria: Lair of Behemoths.

[peteroupc]

With Ikoria: Lair of Behemoths, the rules for the Commander variant changed in a manner that affects this question. According to the changed rules, in the Commander variant, you can't bring a card into the game from outside it (whether by the companion ability or otherwise) if—

• the card has the same name as a card in your starting deck (including your commander [C.R. 903.3]) or a card you already brought into the game, or
• the card's color identity includes colors outside your commander's color identity

(C.R. 903.11).
As a result, for example, in a Commander game you can't cast Gyruda, Doom of Depths from outside the game (or otherwise bring Gyruda into the game from outside it) even if Gyruda is your chosen companion, unless—

• your commander's color identity includes blue and black,
• your starting deck's commander was not named Gyruda, Doom of Depths,
• your starting deck otherwise had no cards named Gyruda, Doom of Depths, and
• you didn't already bring a card named Gyruda, Doom of Depths into the game from outside it.

EDIT: Clarification after comment 5 was posted.

[Cardwielder]

Does your commander count in the starting deck?

[peteroupc]

Does your commander count in the starting deck?

Yes (C.R. 903.3). As a result, if you want to declare a "chosen companion", your commander and other cards in your deck must comply with that companion's deck-building restriction. In a Commander game, you can't bring a card you own into the game from outside it if that card has the same name as a card in your starting deck (including your commander) (C.R. 903.11).