A One-Round Living Greyhawk Shield Lands Regional Interactive From the introduction: Who are the Green Masters? And why have they come to the Shield Lands? Perhaps the invitations they have magically posted in taverns everywhere might provide a clue: “Come one, come all, to the Greatest Show on Oerth! Come see the Contest of Champions, the Mammoth Muddle of the Mighty, the Rumble on the Ritensa! Adventurers of all creeds and experience particularly welcome. Your friends, the Green Masters.”