палочка-выручалочка(Букв. "волшебная пуля". A simple remedy for a difficult or complex problem, especially a cure for a disease.
• In recent years, penicillin-based drugs have lost some of their magic bullet status due to the rise of antibiotic-resistant bacteria.
History shows that there's no magic bullet for a global financial crisis.wiktionary.orgAlexander Demidov)