• A new way of playing Heart: flee the Ministry after they’ve turned against you and make your way to the City Beneath
• Origins for each Spire character class that allow them to function as characters in Heart
• More information on Derelictus, the City Between, giving players the chance to explore it as though it were a series of landmarks and delves
• The Minister calling, which allows players to quest for fragments of Our Hidden Mistress
• Four new spells for those devoted to the dark goddess
• Active Operations of the Ministry in the Heart, each a plot hook for a zealous character or crew

A copy of Heart: The City Beneath is required to use this book fully.