Avernus vs hellfire

Avernus

name
  • A lake in Southern Italy. 

  • The entrance to Hell or the underworld, or the underworld itself. 

hellfire

intj
  • hell; damn; blast 

adj
  • Of or relating to a violent, apocalyptic and ultimate day of reckoning and judgment; usually characterizing a form of Christian preaching. 

noun
  • The fire of Hell. 

  • Fire produced by the Devil, or a similar supernatural creature connected to Hell. 

  • A fire that burns with unusual heat or ferocity. 

How often have the words Avernus and hellfire occurred in a corpus of books? (source: Google Ngram Viewer )