Sisters of Battle
In the tabletop miniatures wargame, the Sisters of Battle are a playable army.
Tabletop game mechanics
The latest ruleset for the Sisters of Battle is available in the Codex: Adepta Sororitas, which was published as an e-book.
Many units possess an ability called an Act of Faith. Once per game, a unit may employ this ability to grant herself and her comrades a particular buff for one turn, provided she passes a Leadership test.
The Sisters possess no psykers among their ranks, but they are allowed to use psyker auxiliaries.
The Sisters of Battle are not superhuman like Space Marines, but they do wear power armor and wield similar weaponry. They have a fondness for flame weapons, as they see great symbolism in "cleansing fire", which orientates them towards short-range combat. In the later releases a so-called Holy Trinity of bolter, flamer, and melta became a staple of their weaponry.
Overview in fiction
In the 32nd millennium, the then head of the church, Goge Vandire, launched a coup d'état which plunged the Imperium into a terrible civil war. After the usurper was deposed, the Imperium decreed that the church could no longer maintain any "men at arms". A literal interpretation of the wording of this decree left a loophole permitting an all-female force. In the 36th millennium, the church established the Adepta Sororitas.
The Sisters are led by an Abbess and are organized into Orders. There are Six main Orders and a host of smaller orders. As the militant arm of the church, they are tasked with suppressing witchcraft and heresy, and guarding the Imperium's shrine worlds. They often work with the Inquisition, as their responsibilities overlap.
The Adepta Sororitas has been a part of the fiction since the beginning, appearing in the original rulebook, Rogue Trader.
The Sisters bear a resemblance to several knightly orders from Medieval Europe, such as the Templers and have a strong Gothic feel. Many of their heroines have the personae and attitude of Joan of Arc (especially in Martyrdom and Sainthood). Being an elite army of female zealots, they also bear some resemblance to the Fish Speakers from Frank Herbert's Dune universe
The design of the models themselves have a strong fire motif. They also take the Gothic appearance of the Imperium to the extreme: the Exorcist tank is shaped like a pipe-organ on treads. Forge World produces alternate versions of their tanks, which have a more "military" and less gothic look.