Hogwarts: Felix Felicis

Felix Felicis is a magical potion that allows the drinker good luck for a limited period of time, during which all things they try to do will be successful. Harry Potter received a small vial of Felix Felicis in Harry Potter and the Half-Blood Prince, as a result of making the best Draught of Living Death potion in class (while utilizing tips from Severus Snape's old textbook). Using Felix Felicis proved crucial to gaining a memory from Professor Slughorn about Voldemort's interest in horcruxes that will drive events to destroy these evil objects in Harry Potter and the Deathly Hallows.