Felix Felicis

Felix Felicis is a potion that is "Liquid Luck". Felix Felicis makes the drinker lucky for a period of time, depending on how much is taken, during which time everything they attempt will be successful. It must be used sparingly, however, because if taken in excess it causes giddiness, recklessness and dangerous overconfidence. It is highly toxic in large quantities, and is also a banned substance in all organised competitions such as Quidditch, along with all other methods of cheating. It is very difficult to make, disastrous to get wrong and must stew for six months before it is ready to be consumed.

History
"Trust me, I know what I'm doing. . . or at least, Felix does."

- Harry Potter after drinking Felix Felicis

In September of 1996, Harry Potter won a small vial of Felix Felicis from Professor Horace Slughorn for perfecting his Draught of Living Death. He later pretends to add a small amount to Ron Weasley's drink at breakfast before a quidditch game so that Ron would feel more confident about his abilities. Ron plays a near perfect game, and Harry later tells him that he didn't give him the potion at all, and that Ron played that well all by himself. The potion was later used in attaining an important memory from Slughorn, and in the battle against the Death Eaters in their invasion of Hogwarts School of Witchcraft and Wizardry.

Appearance
This potion has a shining gold appearance, resembling molten gold. When completed, small droplets leap like goldfish above potion's surface when it's inside a cauldron. Despite this description in the books, in the films the potion was transparent in colour.

Effects
Felix Felicis possibly works by providing the drinker with the best possible scenario. This usually registers in the drinker's mind as an unusual urge to do 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 choose not to obey whatever the voice tells him to do. This is easily remedied, however, as the potion does not single out only one scenario, but changes paths as the situation unfolds.

The potion's effectiveness seems to wane as it is close to ending completely, as when Harry was making his way back to the Gryffindor Common Room, he ran into Peeves, but was able to dodge him due to the potion, but only barely.

Harry's use
When Harry Potter used Felix Felicis, several events occurred that were beneficial to Harry and his friends; the main being Harry obtaining the memory from Slughorn.thumb|250px|right|Harry Potter using Felix Felicis in 1996.
 * Harry obtained the uncorrupted memory from Horace Slughorn about Horcruxes. During this adventure, evidence of luck was following him.
 * Harry was able to not let down his friend Hagrid and attended Aragog's funeral.
 * Filch had left the front doors of the castle unlocked.
 * Slughorn was tempted to accompany Harry to Hagrid's by the possibility of obtaining valuable Acromantula venom.
 * Harry was able to use a non-verbal refilling spell, even though non-verbal spells were new to him, so Slughorn would not run out of drink.

Etymology
Felix is the Latin word meaning happy or lucky. 'Felicis' is from the same root, but declined in the genitive case. It is translated as 'of luck.' Therefore, Felix Felicis means 'Luck of Luck' or 'Luck's Luck.'

Behind the scenes

 * In Harry Potter and the Half-Blood Prince, Felix Felicis is described as looking like liquid gold. In the movie it has only a light gold hue.

Appearances

 * Harry Potter and the Half-Blood Prince
 * Harry Potter and the Half-Blood Prince (film)
 * Harry Potter and the Half-Blood Prince (video game)