Even magic systems have pros and cons, which is one way to further define our system(s). Some pros have little to do with the type but rather the society. For example, if training or materials is widely available or cheap, that’s a plus and may result in easier refinement of the talent. On the other hand, this could also result in numerous practitioners so that it’s harder to gain employment as one or distinguish oneself, for example. There may be pros and cons that are specific to the type, rather than general benefits of wizardry. For example, many practitioners can help their community, or make a difference in life, finding meaning and purpose in their powers, but this is true across magic types. We’re looking to define what’s beneficial about a type.
Why does anyone want to perform this type of magic? If they don’t get to choose between types, this matters less, as they only have one option: develop their talent/ability or not. Reasons to forge ahead can include the obvious ones, like power, prestige, wealth, personal safety, and gaining advantage for ourselves or others, but even if none of these appeal to someone, there’s a default reason: they have an innate ability and may sometimes cause things to happen by accident, so they need to learn control.
Regardless, we should craft some benefits of each magic type. A built-in benefit might be that a necromancer can communicate with the dead and possibility comfort the living by fostering interaction. If the dead have advance knowledge of the future, this can also be advantageous. Alchemy is thought to cause noble changes within a person, whether the practitioner or the target, and doing so may align with a person’s outlook to make the world a better place; it’s the similar set of reasons for why people become priests. For an elemental wizard, bringing rain to a barren land is an example. Psionics can help us understand each other or avoid problems. To craft these, consider what uses practitioners have for this magic. What are their goals? What can be done with it?
Our intended story, if we have one, can also assist. What problems will the characters face and how might this magic type assist them? If a trap lies in their future, perhaps they can see it in advance. If they can’t find an item physically, maybe this wizardry can locate it. Reading minds helps overcome an enemy, or creates allies. How can they resolve conflict? Be careful not to perfectly solve the plot or character issues with magic!
While pros don’t help us craft limits to define a magic type, they can help us envision cons that do by way of contrast. And these benefits are only possibilities, not guarantees. The cons can prevent realization of these benefits.
What problems does this magic type pose? All types can be dangerous, so we’re once again trying to decide on specifics for a type. Reasons to not develop the talent can be economic, lack of education, lack of materials, social problems caused by being a practitioner, personality traits (lack of desire, follow through, and more), or other problems inherent to the type.
Necromancy can revive the dead, who may have ideas of their own about obeying commands or what to do now that they’re animated. They may now have supernatural traits that can harm the necromancer or expose the practitioner to knowledge that haunts them. Some types like witchcraft may require a bargain with an evil entity like a demon, who eventually comes to collect. Either of these could result in prolonged contact with other conscious forces (demons, ghosts) that increase the risk of being compromised by them. We could become enthralled by them, enslaved. We might die and our spirit enter their world. To avoid such fates, a spell may have a time-limit on it.
Practitioners aren’t the only ones for whom problems can be caused. Do I want a clairvoyant in my head? Is society okay with necromancy? A government or high-minded individuals can place limits, not simply by creating laws, but by incorporating limits in the spell. Imagine that our wizard Kier, who invented Kierzardy, tried to protect himself, devotees, or people in general by adding the limits. Or maybe he didn’t and decades later, a government hires a disciple to alter the spells and does so, with older versions being confiscated. This thinking allows us to imagine catastrophes and then what people did to imbue spells with limits.
Our intended story can help us determine problems. What sort of issue might the character face because they have this talent or ability? Breaking laws is not what we’re after, but magic going wrong and causing problems. Practitioners may have imposed limits on the magic system in order to avoid all of these problems might have resulted in limits being imposed on the magic system by practitioners, or the spells’ creators, or those who control the source of the energy (such as gods).