Tribal Traditions and Commandments
The Great Dream is not the only magical force in Nurna. The same way all dreams are part of a whole (the Great Spirit), so are laws and traditions from Nurns. In Nurna, disobeying the tradition of your people is more than a legal tresspassing or a shameful disrespect: it is dangerous and an easy way to attract the corrupting force of the Dark One.
Thanks to the Great Dream, Nurna's races can understand how the world works and how the Dark One manifests. This allows them to create protection tools, which can be magic and rituals but traditions and commandments too. With these tools, they avoid the corrupting forces that flow anywhere in the world. Through astral travel, prophecies and communion with the gods, each tribe has written its own rules, suited to them, and with these rules they keep away the trickster force of the Great Selfish One. These laws are more than a list of "to do and not to do": they yield power. Follow them, and you'll be safe. Disobey them, and you will fall. This sets of magic laws can appear in two forms. Some of them have the look of customs that are passed on from generation to generation. These are known as Tribal Traditions. Other magical laws appear as religious obligations, dictated by the priests, in the name of the gods. These are called Commandments. Every person in Nurna, whatever the race, lives under one or two Tribal Traditions, and sometimes under one Commandment too. By fulfilling them, they hope to dodge the ever present vortex of the Dark One. They believe Traditions and Commandments will stop the disasters that the Dark One unleash on the world. Of course, some people do not fulfill these Traditions, and many disregard all Commandments. Many of these come out unscathed, but there a lot of people who end their days corrupted by the Taint of the Dark One, even without realizing it. It's very difficult to go back once the darkness of the Great Selfish One has touched you.