Fridge Horror
Nix's speech about how "the Fire" gave him his mission to cleanse the world, and the reality of magic's existence, alludes to otherworldly forces influencing the realm of mortals. In the short story the movie was based on, it was established that Swann bargained with dark forces and demons in order to be able to perform true magic; while the movie never explicitly states the source of Nix's powers, they are strongly implied to be infernal in origin (q.v. his power over and fondness for fire, his perversion of religious imagery, and his obsession with death and corruption). In light of this, one has to feel dread at the entirely logical possibility that Nix was far from the first or only true magician in history — Swann's claim to have learned about magic from books beyond Nix's teachings indicate that there are other ways of gaining power, and someone even more destructive than Nix may at some point discover them.
