set on vs zerg

set on

verb
  • To attack. 

  • To be determined to do or achieve something. 

  • To encourage someone, or an animal, to attack someone. 

zerg

verb
  • To attack an opponent with a large swarm of units before they have been able to build sufficient defences. 

noun
  • A very large group of units or players. 

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