If you're using the FAQ, Corbulo's rolls can't be used *before* the game starts for any reason [game type] because a neutral player is rolling it. You can logically apply that reasoning towards ending the game - no one is actually rolling that dice, therefore you can't do it, RAW.
However, RAW, you should be allowed to roll the "who goes first" die as you are actualling rolling it against your opponent, who is also rolling. However, the FAQ denies that as well.
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