Running the Game
GM References
Ready-to-run stat blocks, from mundane animals to things that shouldn't exist.
Adversary Catalog
Adversary Index
Ready-to-run stat blocks: mundane animals, plus a reusable Dire/Giant/Mutated variant template.
Cryptids
American folklore creatures, treated as real but rare in a modern setting.
Nightmare Creatures
Original urban-fantasy and horror archetypes, built entirely on the system's own mechanics.
Quick Reference
Tools
Part of the 20 Below core rules. Source and full history at github.com/feralucce/20_Below.