Rules glossary
903.11 Except via rules, special actions, and effects that specifically bring cards into Commander games from outside the game, traditional cards from outside the game cannot be brought into a Commander game.
- 903.11a If a player is allowed to bring a card from outside the game into a Commander game, that player can’t bring a card into the game this way if it has the same name as a card that player had in their starting deck, if it has the same name as a card that the player owns in the current game, or if any color in its color identity isn’t in the color identity of the player’s commander.