Database: card_games
Question: List all the card id and artist with unknown power which are legal for commander play format.
SQL: SELECT T1.id, T1.artist FROM cards AS T1 INNER JOIN legalities AS T2 ON T1.uuid = T2.uuid WHERE T2.status = 'Legal' AND T2.format = 'commander' AND (T1.power IS NULL OR T1.power = '*')