It's the end of the year again and time to re-assess what I am actually playing or want to play in the near future. To help evaluate and purge the current game shelf, I often turn to the "cast away" scenario. You are about to be indefinitely stranded on a remote island with gamer pals...
Assuming that you play d20 in many genres with slightly different rulesets (fantasy, modern, sci-fi, etc.), which singular monster book would you choose if you could only have one for all d20 gameplay?