firebomb vs immolate

firebomb

verb
  • To attack with a firebomb. 

noun
  • A weapon that causes fire; an incendiary weapon. 

immolate

verb
  • To destroy, especially by fire. 

  • To kill as a sacrifice. 

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