In addition to the Gods listed elsewhere, there are several minor mythological beings spoken of in current Western culture and may be taken more or less seriously. These are commonly called Kitchen Gods.
The Twilight Tunnels, the Imperial Gate system, were the backbones of the Imperium. The ability to travel almost anywhere via the Twilight Tunnels, allowing for near unlimited trade for little money, quick communication (any message anywhere nearly instantly (or within 3 days for the hinterlands), and easy personal travel. This system can be adapted to any gate system.
Food is Life. Food, what is eaten, when it is eaten, and how it is eaten, says a great deal about a culture.
Every culture has a different idea of what constitute’s breakfast. Even regions inside the same culture can vary quite a bit (like grits with hot sauce in Texas or Fishcake mix in omelets in New Hampshire). What do they consider “food” first thing in the morning in your space?
The Seeker was a mystic guardian from long ago. He was a hero and a companion to Greater Heroes. To ensure the Realms would be protected, he charged his apprentices to teach others.
BlenderofSixElement’s Way is the system of magick known to all the known world of Arth. There may be native minor magic systems, but the only effective system is BlenderofSixElement’s Way.
They were a very religious people, focused upon their leaving to the afterlife. They associated magical spirits/ gods with birds. It is difficult to determine if this was metaphorical or actual.
Shadows, Mirrors and Flames. Three things we have all seen and not given much thought to. What if in each of these things you could find entire alternate planes of existance? Shadows move but what they are shadowing does not. Mirrors show us what others can easily see. Flames dance and twirl inviting you to dance only to scorch you when you get close. These three things hold much mystery. What if you could harness their powers? Heh...