Mageblight

The Beginning
The power of the bygone Belvarian Kingdom largely came from the immense wealth of its capital, Daea. The city had an excellent harbor on the Kesvarian Sea and straddled the border between two continents, thus linking lucrative trade by both land and sea.

The Belvarian military was the largest of its time, but the kingdom was becoming increasingly threatened by the burgeoning magics of their enemies. In response, Belvaria established the College of Arcana in Daea to better understand magic and to defend themselves from it. King Bertram, the Last King of Belvaria, desired to expand their boundaries with the power of their mages. His daughter Eliza, a prodigy at the College, knew there was much they didn't understand, but the potential was there. In her studies, she heard of a place overflowing with magical energy, a plane known as Limbo. She was eager to please her father and in 1142, she haphazardly tore open a portal to this plane and brought about the Mageblight.

Pure chaos spewed forth from the dimensional gate, tainting the region with odd phenomena. Shifts in gravity hold once grounded mountains aloft. Violent storms bombard the landscape. Time seems to stand still in the north where it's perpetually winter. Belvaria was ill prepared to handle such devastation. Daea, nearest the portal, was quick to fall, and with it, the rest of the kingdom.

Much of the wildlife died off as well. Over centuries, what survived underwent rapid adaptation. Some species are merely echoes of their ancestors, some are largely unchanged, and others are believed to actually be entirely new species that crossed over from Limbo.