Magic
Aspects
An aspect is defined as a specific type of light, manifesting as a single (magical) element. Each person is born with the potential to conjure manipulate a single aspect, and it cannot be changed. For example, someone with a water aspect is able to transmute pure light into water and control it at will. This person could also control water that is already present, such as from nearby rivers and oceans.
There are nine aspects of light present in Luxos—earth, fire, water, wind, thunder, ice, bloom, radiance, and umbra. What aspect a person has can only be identified when it is casted, and generally cannot be "read" through other means.
The ability to use magic isn't just limited to people. All creatures and even some plants can cast as well!
Aspects are powerful and versatile, and society has explored many applications and techniques over time. However, despite its great potential, there is a limit to one's ability to use an aspect: as one uses it, a dangerous waste byproduct called "cael" is collected in the bloodstream where light once flowed.
Cael
Cael is a substance that manifests in the bloodstream in the place of light when magic is used. Like light, the composition of cael is not entirely understood. Low cael buildup manifests as exhaustion, fatigue and muscle aches. Though cael within the body will dispel on its own eventually, rest and hydration will quicken the recovery process. The rate at which people dispel cael and their casting limit before exhibiting any symptoms varies between individuals. Even siblings may find that their cael limits are dramatically different.
It's also been noted that spending time around other people, particularly loved ones, increases the rate at which someone recovers. Though concrete explanations are yet to be found, some speculate that this is due to a community survival instinct present in which people subconsciously "share" their light with each other. It's a nice sentiment, even if it doesn't really feel like it should be possible.
In higher accumulations, cael may cause an individual suffer a condition known as caelism. Common tells for caelism include severely weakened or impaired bodily functions (such as difficulty breathing or ceased injury recovery) and a telltale "bruising" or "blighting" across various parts of the body. Caelism takes a significant amount of time to run its complete course before it is dispelled, and scarring from the blight may remain even after a full recovery. Medicine exists to increase the rate at which cael is dispelled, but it's better to just never let things get to this point in the first place.
Though caelism is very dangerous, prognosis is rarely ever certain death. Caelism initially presents itself in a localized area—if aggravated, it will travel to the heart, where it will likely evolve into a curse or become fatal. Once symptoms are recognized, it is recommended that anyone with caelism find immediate medical care and rest accordingly. Of course, it's also considered common sense to avoid using more magic at all costs once caelism manifests.