About reeking havoc vs wreaking havoc
“Reeking” means “smelling strongly,” so that can’t be right. The phrasesimply means “working great destruction.” “Havoc” has always referred togeneral destruction in English, but one very old phrase incorporatingthe word was “cry havoc,” which meant to give an army the signal forpillage. To “play havoc with” means the same thing as to “wreak havoc."Avoid as well the mistaken “wreck havoc."
Source: http://www.wsu.edu/
