silver bullet
From Longman Dictionary of Contemporary Englishsilver bulletsilver bulletAmerican English something that solves a difficult problem very quickly and easily There is no silver bullet for this problem. → silverExamples from the Corpussilver bullet• More investment isn't a silver bullet for poor neighborhoods.• A pilot scale rig dedicated to the exploration and development of the silver bullet process has been fully operational for some months.• Perhaps silver bullets would have done the trick.