The first stage of "The Battle of Carn Dûm" has the following text:
Do not discard unresolved shadow cards at the end of the combat phase.
Mi question is... what happens if the players manage to have enough engaged enemies, all of them in forest snares, to have all cards in the mission deck assigned as shadows ? (Or even in the victory pile thanks to out of the wild, leave no trace, none return...) I know... it's a very weird situation, but I think that in a 4 player game, if decks are focussed on it, it can be possible.