https://www.fantasyflightgames.com/en/news/2018/11/30/the-wages-of-sin/

I really like the idea of "Spectral" alternate locations with their own encounter deck!

I wonder how they'll include the new card that they announced then... Will it be shuffled into both decks? Will it be distributed randomly?

Reading the card text, it appears to start in the "standard encounter deck," and then migrate into the "spectral encounter deck," where it can do damage and bounce back to the standard deck. Maybe the spectral deck will start empty (or tiny) and get filled by these sort of effects?

For the initial seeding of spectral deck they could do something like: Start with one copy each of <N named cards>. Randomly select <N-2> to form the spectral deck, shuffle the remaining 2 back into the main encounter deck.