If you have read the mortal instruments you can just skip
Nephilim, often referred to as Shadowhunters, are a secretive race of humans born with angelic blood. They are ademon hunting race that has survived for over one thousand years. They have fought the demons valiantly, creating their own culture and civilization. Their mandate is to protect humans.
If the Mortal Cup is reversed, it will be transformed into a demonic version known as the Infernal Cup. Using the Infernal Cup can turn Shadowhunters into Dark Shadowhunters. All you need, as demonstrated by Sebastian andAmatis, is demon blood and the Infernal Cup. When a Shadowhunter consumes it, that person will become corrupted.
