Demons of Shadow: the demons that Johnathan mentions here will be explained in a later chapter. I don't wanna spoil anything this big.
Nightrunners: People cursed with the Night's Rune. Basically the equivalent of being turned into a Bat pony.
Runes: There are three main branches of runes, Dark runes, Neutral runes, and Light runes. (Which are the ponies cutie marks if you ain't guessed it. But they are done entirely in black ink. Like tattoos, but certain words and events must be done before the runes have any power.)
Dark runes: Dark runes are basically the equivalent of dark or black magic. Often times they are required to help the humans to survive certain threats. (Dragons and timber wolves for example.) However they carry taint.
Light runes: The polar opposite of the spectrum from the Dark runes. Used mainly to heal wounds and create armor.
Neutral runes: Grey magic. Main uses include, but are not limited to, telekinesis, telepathy, and music.
Taint: The aftereffect of using, or being subjected to the use of, a Dark rune. Johnathan has three dark runes himself. One is his own, the other one is on the base of his head. It is shaped, and colored, like a cotton candy cloud with chocolate rain going into it. It allows him sense of coming danger. Though he never can discern the source or magnitude of said danger. The second is weird. It protects him from the taint of the other one, but causes him to go into unexplained fits of anger or sadness.