In fantasy, potions are a very handy way for magic to be administered to someone without expending a lot of energy, and potentially without them knowing magic was performed at all, and without revealing who did it.
The term occult is defined as the search for secret knowledge, usually in reference to trying to seek out the secrets of the universe.
Nature magic has the wonderful ability to be beautifully simplistic in its execution while being stunningly vast and complex in its scope. The magic might be tied to plant life, to the seasons and changes of season, to the weather, or to all of these things together.
The effects of celestial bodies are so subtle that we often don’t realize them in our daily lives, and yet they are there. If you live on or near a coast, you are probably more aware of them because of the daily ebb and flow of the tides, which are caused by the pull of the moon’s gravity on the earth.
For the most part, in fantasy worlds, the legality of magic is a given. It’s fantasy, so there is magic, and with many people using magic regularly, it must be normal and good, right? Well… it doesn’t have to be that easy.
In fantasy worlds, kitchen witchery is some of the simplest magic. It’s more magic of desire vs. intent. It’s magic that can be accomplished with anything one might have in their kitchen, by people who have no formal training.
What does a magically-aided journey look like? In many fantasy stories, it looks like a portal from one world into another, such as the wardrobe in CS Lewis’ Chronicles of Narnia.
Not all magic requires instruments, but as you develop your magic system and get to know the characters of your story, you may find that it’s easier for your magic practitioners to have a tool which helps them utilize their magic.
Healing might be a tricky form of magic, depending on the established rules for your world so far. In addition to magical knowledge, the practitioner will likely need anatomical knowledge as well.
No matter what type of magic exists in your world, or how it is utilized, knowledge of it will be accumulated and compiled. Magical knowledge is often treated a bit differently than academic knowledge in general, since in the wrong hands it might be very dangerous.