do battle vs mix it up

do battle

verb
  • To engage in a fight; to battle. 

mix it up

verb
  • To compete vigorously, to quarrel, or to fight physically. 

  • To create one or more variations of the usual way in which something is done. 

  • To engage with people, relate to people. 

How often have the words do battle and mix it up occurred in a corpus of books? (source: Google Ngram Viewer )