Decima Town's underground subway system is now its lifeline. Mefitis Underground was an abandoned subway line, only half constructed, and it became a haven for the poor and unwanted. Now, it's also proven as defensible as a bomb shelter, it's the only place left in Decima Town where neither the scourge nor the poison kill you dead. Mefitis is a very small, very miniature version of a town, complete with its own shops and services.