Necromancers' Nectar

Necromancers Nectar, also known as Necromants Nectar, is a mysterious substance that was devised by the Nightmare Knights to be used to enter the Pits of Inferno.

Since the Knights did not want anyone from the forces of evil finding their way into the Pits they designed the entrance so that only those who would "Feed those in need" could enter. While this phrase is still a mystery it is likely that a greedy and selfish member of the Brotherhood of Bones would never help someone and would not "feed those in need" and could consequently not enter the Pits. It is therefore possible that Necromancers Nectar is some "food" or sustenance that will feed the needy, and this is something that evil will not do.