When the Gravediggaz emerged from hip-hop's crypt three years ago, they were credited with ushering in a new wave of scary rap known as horrorcore. Thankfully, the group has survived that short-lived trend, which generated more schlock than shock. On the Gravediggaz's second album, The Pick, the Sickle and the Shovel, Poetic, Frukwan, Prince Paul (of De La Soul fame) and RZA (of Wu-Tang Clan)...