Dark Water is what Dr. Blakk uses to turn regular slugs into Ghoul Slugs . Dark water can be mined from deep within Dead weed cavern or drilled for in deep places like the Under town. In Episode 5 when some miners were exposed to dark water they took on a ghostly appearence until it was capped, that is when they returned to normal. Slugs are afraid of it. The Cave Trolls know about Dark Water and named is Conru Nuzu.