A world most Strange. (RP Plot and Lore)

Storyline

A millennia ago, war between four nations broke out and caused great calamity. Each of them possessed 4 beliefs: Life, Death, Light and Dark.
Tod, the Nation of Death. Utilizing in plate and chainmail and broad weapons, including oversized swords and great axes. Their belief is that in death, new life will always take the place in the world and thrive.
Shenghuo, the Nation of Life, producing swords able to slice flesh and bones in a clean slice and the creation of unique weapons. Their bows and arrows can explode upon impact and their explosives are more advanced than even regular cannons. Their belief is that all life is sacred, and must be valued.
Foncé, the Nation of Dark. While their infantry is similar to Tod, their designs are certainly more unique and built for light weight, and rapiers for armor piercing. Their firearms are more advanced and militarized with handheld bombs to use. Their belief is that darkness is within everyone, including humanity itself.
Valo, the Nation of Light. To survive the harsh winters and snows they fashion themselves large wool or fur coats to wear. Their helms are made of a special alloyed steel for sturdiness and fur lined on the inside for warmth. Their belief is that light conquers all, no matter what.
Conflict sparked between the four nations, dragging in the land know as the "Mid World." Due to the heavy wars and bloodshed, all five of the nations fell from great countries to nothing but barren wastelands. In the end, none of them won. Anyone who visits may never return, for nothing could live there... nothing pleasant...
1,000 years later, two nations took the role of empire, now allied to protect those under their rule. Firearms, while not always reliable, have made grand advancements and improvements over the millennia. But now an epidemic sweeps through the known world. The disease, known as the Calor, has terrorized millions in even the most stoic. The valor causes orange veins to appear and glow on the body, acting as if burning embers. This can cause someone infected to have a significant rise in body heat, causing them to die of a heat stroke, dehydration (through sweat), or spontaneously combusts. While not common, it's still a terrifying idea...