A rugged and dangerous world, Fortis orbits a binary star. Violent storm sweep across the surface, whipping sand and sea spray against the mountainous landscape. Tremors split open the ground, spitting molten rock and scalding geysers far into the sky. Swirling clouds of volcanic smoke turn the rain acidic and huge cave systems have formed as a result. Rivers course through the ravines and crevices, driving caustic floodwaters into the caverns below.
The Forteans developed magic to protect their civilization from the harsh environment. Without their spells and sigils, the huge towers and labyrinthine underground cities would collapse and wash away. Indeed, over the course of history, such disasters have struck, sometimes being brought about by sabotage or warfare.
Approximately every 250 years, the planet moves from being in the light of one sun to the light of the other, and a great shift in magic takes place. There are two major factions of magic users and their prevalence alternates with the sun. However, both are necessary for society to continue since neither is strong enough during its dormant cycle to protect the cities. Both must train recruits in their traditions at all times to preserve the knowledge necessary for the next turning of the sun.