Can you switch your chosen champion between rounds in a tournament if both champions are in your main deck?

Ruling: You cannot switch your chosen champion between rounds. You can only change it after the first and second game of each match, which is when you can also switch out cards between your side deck.

Sequence:

• Champion switching is allowed after game 1 of a match
• Champion switching is allowed after game 2 of a match
• This timing coincides with when sideboard changes are permitted

Nuances:

• Both champions must be in your main deck to be eligible for switching
• Switching is not allowed between tournament rounds, only between games within a match