"If a hero is in its controller’s discard pile at the end of a scenario, that hero’s name is added to the list of Fallen Heroes and its controller may choose a new hero when setting up the next game. The new hero is recorded in the Campaign Log and each player receives a permanent +1 starting threat penalty for the rest of the campaign."

If a hero is in the discard pile at the end of a scenario...can be used again for the other scenarios? Or we MUST select another hero?

1 hour ago, bitzurock said:

Or we MUST select another hero?

You could always choose to not add another hero, continuing with the ones that survived, but if you want to go back up to three heroes you cannot chose a hero from the list of Fallen Heroes.

Thanks!