Lady Myrchella Sinderfell is one of the most ellusive and destructive heretics active in the Calixis Sector. Intelligent, resourceful, and cruel, over the centuries Myrchella Sinderfell has sampled blasphemous pleasures, dallied with diverse heresies, and committed atrocities of the most vile nature for no other reason than her own gratification.
Born into the high Sinderfell family of Scintilla, Myrchella Sinderfell was raised as part of a lineage whose wealth and holdings spanned the Calixis Sector. It is said that in her younger years she showed exceptional promises in all areas of education, with no sign of the madness to come in the first decades of her life. When she came of age, Myrchella used the Sinderfell wealth to assemble a vile court of sorcerers, xenophiles, flesh crafters, and corrupt savants in the seclusion of the Sinderfell manse on Quaddis, collecting them and their knowledge like a true dilettante of the vile. The corruption of Lady Sinderfell was finally betrayed to the Inquisition by one of her mistreated servants.. The Holy Ordos razed the Sinderfell manse in a single night—it is said that the fury of the assault could be seen from the balconies of far Xacarph.
Lady Sinderfell escaped the wrath of the Imperium to recreate her blood-soaked court of blasphemy over and over again. On Malfi she suborned the leadership of a sanguinary cult and bathed in blood every day for a year. On Kalf she and her entourage burned town after town, hunted the survivors through the night, and unleashed unclean spirits to plague any who remained.
Myrchella Sinderfell is known to draw around her a court comprised of heretics. These heretics have included rogue psykers, warp dabblers, xenophiles, hereteks, dissolute nobles, corrupt Navigators, scholars of the proscribed, and dealers with daemons. These courts are rarely enduring and are often discarded in flight or destroyed for diversion by Lady Sinderfell herself.
Sinderfell prefers to assume the identity of others and corrupt families, cults, and organisations to her own ends (usually including murder and wanton infliction of pain). She is known to favour numerous devices of forbidden technology, some of xenos design, to further her proclivities. Though reported as killed on board the Phoenix’s Ransom by Judge Uzzriah, and again in the Castigation of the Red Vaults of Luggnum, Lady Myrchella Sinderfell is still believed at large in the Calixis Sector.
Myrchella Sinderfell’s avarice, spite, narcissism and sadism are obvious and reflected in every part of the heresies that have made her notorious. She has wallowed in gore, inflicted pain, and darkened her fractured soul not for an ideal but simply because it makes her “happy.”
Source: Disciples of the Dark Gods Page 191