An effect created by the god Adon after the conclusion of the War of the Ban. Due to Gyphon's attempted coup on all three planes, Adon decided to punish the Foul Folk, Black Mages and all other creatures that had sided with him (with the exception of humans). He established the Ban, which would cause them to instantly crumble to dust if they were ever exposed to sunlight.
This severely limited the ability of Gyphon's followers to cause trouble, since they could only attack at night. During the day, they would be forced to seek shelter out of the sun.
The Black Mage Modru attempted to circumvent the Ban by using the Myrkenstone to create the Dimmendark, an expanding zone that effectively blocked out the sunlight. Inside the Dimmendark, the Ban was nullified. After Tuck Underbank destroyed the Myrkenstone, the Ban went back into full effect.
The Ban was eventually lifted when Bair argued with Adon over the necessity of free will.