A dark-side reservoir was a wellspring of evil energy. One such reservoir emanated from the many Sith crystals and artifacts that Darth Sidious kept in the Grand Republic Medical Facility. At the center of that reservoir hung a massive Sith-imbued kyber crystal, slivers from which were be used in Sith lightsabers. When Anakin Skywalker was reconstructed into Darth Vader following his duel on Mustafar, his recovery was aided by an "immersion" in that wellspring.[1]
Sources
- Star Wars: Complete Locations (First mentioned)