Children of the One

"We are the Children of the One and she will rise again, now die and serve her."
This is the only thing that the hooded figure told the scavengers before attacking. The area around Blazeridge has been declared off-limits to the expedition.
This faction, led by Vizor the Black (no one knows his real name or where he came from) purports to resurrect Cimira Kane, a necromancer who started the war between the humans and dwarves and almost wiped out both kingdoms in the ensuing chaos. She was defeated by a combined strike-force of Champions and Clerics of the gods, along with several mercenary teams and an undercover member of her cult who was secretly following Sariel. They managed to kill her, destroy her base and seal away the location of her base at great cost.

This faction has managed to ferret out her base somehow and discovered the only remaining tome (Disparaition - Mastery of Darkness) that had been protected from the destruction.