secret sauce  
noun [ U or S ] uk/ˌsiː.krət ˈsɔːs/ us/ˌsiː.krət ˈsɑːs/
  (SPECIAL QUALITY)      
 秘诀|秘方
a special quality that makes something successful 
  The secret sauce for "going viral" is still a mystery. 爆红的秘诀仍是一个谜。 
 The company is going to need some secret sauce to make the takeover work. 公司需要一些法宝来促成并购。 
 Not protecting intellectual property can lead to someone else stealing a company's secret sauce. 不保护知识产权会让别人窃取公司的秘方。 
 - More examples
 - Every private equity firm has its own secret sauce.
 - The event space, which seats 200, is the store's secret sauce.
 - They were afraid that their secret sauce would leak out and their rivals in the industry would get their hands on this technology.