[Icelander]

For the purposes of Higher Purpose (Tradition), how broad should the tradition of the Nommo fish-men be?

Their magic is primarily useful for manipulating water and things that are found around islands, hunting, traveling and suchlike, but they also know Elder Signs and rituals to keep away the Things From Beyond that intrude into their world.

It's basically an aquatic variety of Druidic tradition, albeit a pretty dark and frightening one, and with a pretty self-serving goal, i.e. avoid being destroyed along with everything else, not a required ethos of protecting nature, like Druidism.