cap it all off vs pour oil on troubled waters

cap it all off

verb
  • To surpass or outdo something. 

  • To finish or complete something; to add a finishing touch. 

pour oil on troubled waters

verb
  • To calm, appease or quieten a person or situation. 

How often have the words cap it all off and pour oil on troubled waters occurred in a corpus of books? (source: Google Ngram Viewer )