Felix Felicis, also called "Liquid Luck" is a magical potion that makes the drinker lucky for a period of time, during which everything they attempt will be successful. However, it causes giddiness, recklessness, and dangerous overconfidence if taken in excess. It is also highly toxic in large quantities and is also a banned substance in all organized competitions, such as Quidditch. It is very difficult to make and disastrous if it is made wrong. Along with that, it requires six months to stew before it is ready to be consumed.
This potion was invented by Zygmunt Budge in the 16th century and proclaimed it as his greatest accomplishment ever. In the book, Professor Slughorn claimed that he used the potion twice in his life: once when he was twenty-four years old, and again when he was fifty-seven, both of which were two perfect days. The potion is said to look like molten gold and while exposed to air large drops will leap like goldfish above the surface without spilling.
Felix Felicis possibly works by providing the drinker with the best possible scenario. This usually registers in the drinker's mind in the form of an unusual urge to take a certain action, or as a voice telling him to do so. The effectiveness of the potion thus depends on the cooperation of the drinker with the voice, for the drinker may for some reason be unable to follow their Felix-induced urges, or can simply choose not to.
This is easily remedied, however, as the potion does not single out only one scenario, but changes paths as the situation unfolds. Then again, the chances of the drinker refusing to follow the urge are very unlikely, as it grows as a "sensation of infinite opportunity" where the person feels supremely confident enough to be infallible for the duration of the Potion's effect.
Felix Felicis also seems to complete the magical power of the one who took it.
Felix is the Latin word meaning happy or lucky. 'Felicis' is from the same root, but is translated as 'of luck.' Accordingly, Felix Felicis means “Luck of Luck.”
