Sin delves deeper into the world of Spire, and includes:
- Two new classes: the divine confidence trickster Gutter Cleric and the necromantic bureaucrat Mortician Executioner
- Extensive sections on the Crime, Order and Religion domains including dozens of new abilities, hundreds of plot hooks and fiction tidbits, and beautiful illustrations by Adrian Stone
- Three ready-to-run scenarios, pitching the player characters headlong into a world of squabbling holy orders, mysterious librarians, demonic artefacts, overclocked noir magic, interdimensional breaches and hotwired avatars to death gods.
A supplement for the Spire RPG. A copy of Spire: The City Must Fall is required to use this book.
