from Saunders’ The Basics of Magic
Since humans possess no innate magic, witches harness it from other sources using spells. Whatever magic they perform requires payment in kind, and over the centuries they have learned to direct it, although they can never be certain what the price the magic will extract. Witches harness magic using four orders of spells: potions, incantations, art, and will.
The simplest order for beginners is potions, hence it is the most common. Witches follow precise recipes to utilize the magic of the potion’s ingredients. With a proper recipe, nearly anyone can mix a basic potion, so witches jealously guard their potions. Although basic potions are easy to master, creating new potions requires extensive understanding of the magical properties of ingredients. Complex potions can be difficult to master and can achieve extraordinary feats of magic.
Often combined with potions, incantations are the next order of spells. Witches speak phrases in the witch’s tongue to wield the magic of the words. Although they must learn the ancient language first, most can perform incantations, so witches jealously guard their incantations along with their potions. Since the witch’s tongue is no longer spoken, creating new incantations requires extensive study and language skills. Complex incantations can take hours to complete and have been known to last for centuries.
More difficult than potions or incantations, art spells require proficiency in both magic and the art required for the spell. Hence, music spells are often performed by bards, picture spells by painters, dance spells by tumblers, and so forth. Certain spells are easier to perform with certain arts, but any of the arts can generally perform the same spells. Creating art spells or performing complex art spells are only done by masters of their art, so new and complex art spells are rare.
The most difficult order of spells are those using will. Unlike the other orders, will spells have no formula and are always new. Witches use their will to gather magic from their surroundings, shape it using their will, then release it with any word or gesture. Witches who can perform will spells are very rare because using the will to perform magic is closest humans have to innate magic. In fact, it is said that all witches who can perform will spells are descended from Rhiannon, the founder of human magic.