In competitions where a sideboard is allowed: 1. A player’s sideboard can include 10 or fewer cards. 2. A sideboard can consist only of valid Main Deck cards. 3. Limits on copies of named cards apply to the combination of main deck and sideboard. 4. A player may change their Chosen Champion to one from their sideboard or main deck that matches their Legend whenever sideboarding would be allowed. 5. See 403 for more information about sideboards.
