Mephistophelian vs atrocious

Mephistophelian

atrocious

adj

  • Very bad; abominable, disgusting. 

  • Frightful, evil, cruel, or monstrous. 

  • Offensive or heinous. 

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