Can you change which version of your champion card is in the champion zone between games in a set, including swapping with versions from your sideboard?

Ruling: Yes, you can swap which version of your champion card goes in the champion zone between games in a set. This includes bringing a different version from your sideboard to the champion zone in games 2 or 3.

Nuances:

• You can swap between champion versions even if both versions are in your main deck
• You can swap to a champion version that is in your sideboard (not in your main deck) for subsequent games