Playing other formats of Riftbound other than the one designated for the tournament with the appropriate registered decklist may not be used to determine a winner.
§ 703.10.b Tournament Rules PDF (officieel)
§ 703 Tournament Errors
§ 703.10 Improperly Determining a Winner [Match Loss]: Games and matches of Riftbound must be decided by playing Riftbound appropriate to the tournament format.
