When folks say "Horrorcore" in reference to raps about the occult, gore, and all around evil shit...cats seem to stop on the East Coast steez with groups like Gravediggaz, Flatlinerz (unfortunately), and then have to resort to namedropping later stuff like early Cage and Necro (shit I'd even put Godfather Don AND Kool Keith as quality producers of the sub-genre). The funny thing to me is, most people don't remember, or never realized, that Big L was easily one of the first on the East Coast to really, really go there with the dark, fucked up, kill-your-mother-then-eat-her-children imagery. I still have an old issue of On The Go (well...by now, what issue of On The Go isn't ancient?) in which they quote L as saying he started the whole "horrorcore" thing on this side of the map with "Devil's Son". I believe it. I'll have to scan that before the week is up.
Here's a great example of L's horrorcorebilities...off of his classic, Lifestylez Ov Da Poor & Dangerous..."Danger Zone".
"Every Sunday, a nun lay, from my gun spray
Fuck Carlito, we doin' shit the Devil's son way"