Shar

Overview
Shar, also referred to as the Mistress of the Night, is a neutral evil greater deity. Counterpart to her twin Selûne, she presides over caverns, darkness, dungeons, forgetfulness, loss, night, secrets, and the Underdark. Among her array of twisted powers is the ability to see everything that lies or happens in the dark. Shar's symbol is a black disk with a deep purple border. Her divine realm is the Palace of Loss in the Plane of Shadow, and her domains are Caverns, Darkness, Evil, and Knowledge.

Worshipers
The clergy of Shar is a secretive organization that pursues subversive tactics rather than direct confrontation with its rivals. In addition to her clerics, Shar maintains an elite order of sorcerer monks who can tap Shar's Shadow Weave. Among her worshipers are the Shadovar (the citizens of Shade Enclave — a floating city which is home to the survivors of ancient Netheril who fled into the shadow plane before Karsus's Folly). Shar holds power over all who use the Shadow Weave.

Orders
In order to gain admittance to the order of the Dark Justicars, a priest of Shar has to have killed a priest of Selûne. Shar's secretive monastic order is referred to as the Order of the Dark Moon. They tap into the Shadow Weave through their powers of sorcery. The Avatars of Shar, or the Nightbringers, are an elite Sharran force. They are spirits that infest hosting bodies, possessing them and using the bodies as puppets. Once one is infected with a Nightbringer that person fuses to being as one with the Nightbringer gaining the strength and beauty of Shar. Only females are selected as hosts for the Nightbringers. Though Nightbringer numbers were large within the Avatar Wars, their numbers fell to the hundreds in the modern day.
 * Dark Justicars
 * Order of the Dark Moon
 * The Avatars of Shar

Relationships
The creation of the Shadow Weave has made Shar the eternal enemy of the goddess of magic, Mystra. This has resulted in the brewing of a terrible war between these two powerful deities.

Dogma
"Reveal secrets only to fellow members of the faithful. Never follow hope or turn to promises of success. Quench the light of the moon (agents and items of Selûne) whenever you find it, and hide from it when you cannot prevail. The dark is a time to act, not wait. It is forbidden to strive to better your lot in life or to plan ahead except when directly overseen by the faithful of the Dark Deity. Consorting with the faithful of good deities is a sin except in business dealings or to corrupt them from their beliefs. Obey ranking clergy unless it would result in your own death."

Literature

 * Mistress of the Night (2004), by Don Bassingthwaite and Dave Gross. It is the second book in The Priests series.