No one remembers how or when it started, the terrible threat of the

night. There have long been stories that spoke of a world in which

shadows were simply harmless tricks of light, something only naive

children feared, instead of a plague that spreads like wildfire during

the hours when the land is bathed in darkness. However, such is now

the talk of myth and legend, for the shadows now breathe, and stir

with a malice that chills the souls of all those left in the wake of

the sun’s course across the sky. The Taint that now pervades all that

which light cannot touch is a far greater threat than any this world

has known, those it touches are horribly disfigured by its fel magics,

and those who allow darkness into their souls feel it wrap around

their minds and drive them mad. The various churches and temples

attribute this pheneomena to the wrath of the Gods, while the students

of the arcane arts speculate it may have been the result of reckless

tampering with the powers of magic, though few care for reasons when

the shadows cast by the moonlight are rapping at their windows,

desiring to devour them, and turn their bodies into vessels for its

dark purposes. Yet, even if the Gods have forsaken this world, there

are still those who are either brave or wise enough to combat the dark

forces that slowly envelope the land. A mysterious call has gone out

to those born with a predisposition to resist the Taint, that they may

be enlisted to battle against it, and fight it back to its very

source. Are you brave enough to free your world from the greatest

threat it has ever known? Are you prepared to join the noble fight

against the Ardent Darkness?

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After that, take a look at your wiki. There is some more helpful info there.

Lands of Ardent Darkness