
Commander creatures you ownCommander creatures you ownAny creature that is your commander, wherever it is. This is how a Background gives its ability to the commander it is paired with. have "Whenever one or more creatures you control deal combat damage to a player, goadgoadUntil your next turn, that creature attacks each combat if able and attacks a player other than you if able. target creature that player controls." (Until your next turn, that creature attacks each combat if able and attacks a player other than you if able.)
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Read from the rules text. A card that enables a keyword makes or is the thing; a card that rewards it gets better when you have it. Two cards interact when one enables what the other rewards.
A Background can be a second commander alongside any creature with Choose a Background.