A disease, unleashed by Sssl, also known as Mother, was an attempt to eradicate the Imperial forces stationed at Fortress Vader on the planet Mustafar. This plague, spread via bites, transformed those infected into mindless automatons, completely subservient to Sssl's will. Ultimately, Darth Vader was able to eliminate Sssl and her drone army by causing them to fall into a flowing river of magma.