The Prophecy of Shadowfall also provides for a way of returning to the light.  The Prophecy tells of a weapon that can be used to banish the darkness…

"A weapon is used in the absence of light,
A sword wielded by the good, pure, and right.
The shadow shall fall before its true might.
A crown on his head from both Man and Elf
The light from his reign is as Truth itself."

In the Kingdom known as the Liberty Commonwealth, the Half-Elven Prince Devon Claymore rules with benevolence. He sees himself as the sword of the Prophecy, and he refuses to take the title of King until, in his own words, "The world has been cleansed of Shadowfall by Our guidance."

The PCs are members of an elite force organized by the Prince with one purpose:  Undermine and destroy the effects of the Shadowfall