The magic system I'm currently working on involves changing limits (name ideas welcome). There are three kinds: physical, intellectual, and metaphorical.
Physical limits are what they sound like. They are the easiest to change. Some examples of physical limits that can be changed:
Noise limit
Lifespan
Growth
Height (this can get gruesome if the upper limit is below someone's current height or the lower limit is above someone's height)
Visibility
Color
How high something can jump
Intellectual limits are the capacity for certain types of thought. These involve changing an individual's abilities and don't impact others. Some examples of intellectual limits:
Perception
Speech
Sentience (it's very difficult to change sentience levels, as it requires raising the intellectual limit of everything in general)
Focus
Ability to communicate
Metaphorical limits are more abstract concepts. They are the hardest to change, but you can get pretty creative with it and set limits on very arbitrary things. Examples:
What something can "find"
Unity (this could make something break apart into pieces on more than just a physical level)
Luck
Truth (this would impact what others believe and potentially reality itself)
What qualifies as "prey"
Time
Changing limits almost always causes additional, unpredictable changes. These can change something's appearance, personality, etc. This makes it incredibly dangerous to experiment with, depending on the limit and how far it is being pushed. Changing the limits of humans is both illegal and wildly foolhardy, so animals are often used in experiments instead. This has led to a variety of creatures being artificially created and embedding themselves in the ecosystem, reproducing and creating a new species. Limits can be changed for living creatures, objects, or general areas. Changing a limit permanently for every instance of it is theoretically possible, but would be incredibly difficult and almost certainly disastrous.
Altering limits requires Luminescence. This is a life force found in all living creatures that floats away when they die. It must be used immediately after death, although ways of storing/transporting it are being researched. This means magic users can frequently be seen carrying around potted plants to kill for their Luminescence. Sometimes killing an animal is required for more powerful changes, as they have more Luminescence. Humans have the most, so those seeking power in nefarious ways might kill someone to change a limit significantly. Theologians are split on what exactly Luminescence is. Some believe it is the soul, others just a strange biological quirk. (I'm not gonna go more into Luminescence for now since that would derail this post )