Complex sentence: Malaclypse the Younger (short Mal-2) is the author of the Principia Discordia, a character in the Illuminatus! trilogy, and most likely a penname used by Greg Hill, comrade of Kerry Thornley (aka Lord Omar Khayyam Ravenhurst).
Split into simpler sentences: Malaclypse the Younger (short Mal-2) is the author of the "Principia Discordia". The name is most likely a pen name used by Greg Hill, comrade of Kerry Thornley (aka Lord Omar Khayyam Ravenhurst).