Potions are brewed with certain ingredients and a specific process of preparation. Misuse of ingredients or an error in preparation may cause any kind of undesirable effects. Some potions are meant to be consumed to be effective, while others can be used to attack the target.
The potions are prepared mainly in fire cauldrons and stored in small bottles. Some potions are required to be used in combination with a spell, but most can do their magical effects without them.