Potions are liquids with magical properties. Brewed with the necessary herbs, spices, or other various ingedients, these magical substances can achieve various effects. Although most potions are liquid, they can also exist in other forms such as gels or powders. The effect of a potions depends on the used ingredients or accompanied spell.
In order for a potion to work, one has to be magical (and possess the ability to brew potions), otherwise some potions might just be poisonous concoction to the drinker.