collision vs showdown

collision

noun
  • An instance of colliding. 

  • Any event in which two or more bodies exert forces on each other in a relatively short time. In a collision, physical contact of two bodies is not necessary. 

showdown

noun
  • The final battle between two nemeses, in which there can be but one victor. 

  • The final round in a poker match, where the all remaining players' cards have to be put down on the table and shown. 

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