Animagus potion

The Animagus Potion is a potion that transforms the drinker into an animal which reflects their personality and traits. If successful, the drinker is then considered an animagus, and is able to repeat this transformation at will for the rest of their life. This potion is a key step to becoming an animagus, and is very difficult, complex and time-consuming to brew correctly, with frightening consequences if done incorrectly. Because of this, many wizards and witches will instead opt for other methods with more practical uses.

Overview
Because an animagus can transform at their will at any time, no one person has to brew this potion more than once.

The Animagus Potion cannot be bought from someone else, as brewing it involves including a piece of one's own hair and a Mandrake Leaf soaked in the mouth of the person who is intended to drink it. Some of the ingredients, however, can be purchased.

Preparation
Almost every ingredient involved in brewing the Animagus Potion involves careful preparation. For example, the Mandrake leaf must be soaked in the drinker's mouth for an entire month without pause, and the dew must be taken from a place previously untouched by sunlight or humans for at least seven days. Overall, at least a month of preparation is required.

Brewing
If executed correctly, the potion will turn blood-red at the instant lightning first strikes during the next lightning storm, signifying its completion.
 * 1) Place the now-soaked Mandrake leaf in a small crystal phial where it is struck directly by the light given off by the moon (if the night is cloudy or the moon is otherwise obscured, the entire Mandrake Leaf process will need to be repeated).
 * 2) Add one strand of hair to the phial.
 * 3) Add a teaspoon of dew to the phial.
 * 4) Add one Death's-head Hawk Moth chrysalis to the phial and place the mixture in a dark, undisturbed place until the next lightning storm.

Physical Appearance
Once completed, the potion is completely blood-red in color. One batch makes approximately a mouthful and only holds enough for one person.

Effects
It is advised to drink the potion in an open, out of sight area, so as to not disturb or startle those nearby who are unaware of the transformation the drinker are about to undergo. They may feel uncomfortable or panicked in a new body, and this may cause them to destroy their surroundings.

Instantly after consumption, they will feel "a fiery pain and an instense double heartbeat". The shape of the creature they will transform into will appear in their mind directly before the transformation.

If successful, the drinker will now have the ability to transform from human to animal by envisioning the animal with the intent of transforming in mind, and vice versa. If unsuccessful, the drinker may experience gruesome half-human half-animal mutations that are permanent, and cannot be fixed.

Behind the scenes

 * It is possible that James Potter, Sirius Black, or Peter Pettigrew did not have to brew the potion because one of the other two did it for them. However, they still would've had to have held the Mandrake Leaf in their mouths for a month.

Appearances

 * Short Stories from Hogwarts of Heroism, Hardship and Dangerous Hobbies