CriticalMoss

We’ve been playing through a campaign of custom maps with consistent characters. Each time we lose, we can no longer use those character roles in future games. Either we’ll beat all the maps with characters to spare, or we’ll learn true humility with the last gasps of our final team. Only time will tell.

The rules are unclear on whether the character cards should be kept in consistent 4-person groups throughout the game (ie: if you draw Holmes, Watson, Stealthy, and Bert on the first round, you will always have those characters on every odd round of the game.)
To make the more dynamic, we like to reshuffle the character deck every two turns, after each character has been played. It may hinder long-term planning in some ways, but it offers more immediate excitement through a variety of character combinations.