foment vs twist the knife

foment

verb
  • To incite or cause troublesome acts; to encourage; to instigate. 

  • To apply a poultice to; to bathe with a cloth or sponge. 

noun
  • Fomentation. 

twist the knife

verb
  • To deliberately do or say something to worsen a difficult situation or increase a person's distress, irritation, or anger. 

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