From the back cover:
In the beginning, all was perfect Darkness and then the perfection was broken temporarily by the Light.
At the moment the Light was its strongest, the Great Darkness returned in the form of the Dark Soul and the murderous Dark Legion.
The first child of the Darkness was Ilian, Mistress of the Void, lover of the Dark Soul, Leader of the Dark Apostles, and through them the Dark Legion itself.
It was Ilian that brought us the dark ages that destroyed our science, nullified our once-sacred technology. She led her brothers against us.
She is the Herald of the Darkness, and if she has her way, the Light will be extinguished again, and the Darkness will reign forever.
Delve into the Dark mysteries of Ilian , the Lady of the Dark Symmetry and the Harbinger of the Dark Soul. This sourcebook is crammed full of details about the Dark Lady herself, her malevolent minions and their foul weapons, as well as how to create a Heretic of Ilian. Plus, there's 30 new, fully detailed Dark Gifts for Heretic characters to use, including new Gifts for the patterns of Ilian. Learn all about what life is like as a member of one of her secret cults, the members of which have infiltrated themselves into every level of the human worlds, including the nearly impervious Brotherhood itself!