This article contnains spoilers for Ahsoka.
Summary
- The Ahsoka TV show reveals that the origin of the Nightsisters' unusual powers is tied to their distant home planet, Peridea, where the Force manifests differently.
- The Nightsisters do not directly access the Force like the Jedi and Sith, but instead use ichor, a substance that allows them to tap into the dark side of the Force and enhance their powers communally.
- It is likely the Nightsisters may have gained their power by taking the blood of the Mortis gods, particularly the Son, who is associated with the dark side. This theory aligns with the visual similarities between the Son and the Nightsisters.
Ahsoka has rewritten the history of the Nightsisters, but Star Wars secretly set up one potential origin of their race 12 years ago. Originally created by Dave Wolverton in his 1994 novel The Courtship of Princess Leia, the Nightsisters of Dathomir have always been one of the most intriguing Force cults in the Star Wars galaxy. The Nightsisters possess powers that are strangely different to those of both the Jedi and the Sith, even more so after they were reinvented 12 years ago upon their debut in Star Wars: The Clone Wars.
The Ahsoka Disney+ TV show has finally explained why Nightsister powers are so unusual. Ahsoka Tano and her allies (and enemies) followed the pathway to Peridea, a distant world on the outskirts of another galaxy. They learned Peridea is the original home of the Nightsisters, presumably meaning they originally learned to tap into the Force in a place where it manifests in a different way. The Ahsoka finale went one step further, revealing Peridea is also associated with the Mortis gods – avatars of the Force itself. Surprisingly, this may be the final piece of the puzzle in understanding the origin of the Nightsisters.
Your browser does not support the video tag. The Nightsisters Do Not Use The Force Directly 
A powerful and ancient Force cult, the secrets of the Nightsisters have long been sought after by the Sith. Their magick is difficult for even the Sith to reverse-engineer, though, because Nightsisters do not actually access the Force directly. Instead, they use a substance called "ichor" as a tool to access the dark side of the Force. This is the reason Nightsisters have seldom been consumed by the egotism associated with the dark side; it means their magick is communal, with their powers enhancing one another, unlike the Sith who are always locked in rivalry with one another.
