Roaming light
Roaming lights are mysterious entities which are integral to higher level spell casting. Their formation is akin to natural phenomena like rain, forming as the result of ambient light forming into one entity. Roaming lights can be found almost anywhere in the Kingdom of Sky.
Roaming light is collected simply by touching it, where it is then absorbed into one's inner light. If meaning to catch the light for someone else to use, it is imperative not to touch it directly.
ID: Piripu poking a roaming light, causing it to be absorbed into his inner light.
Roaming lights come in all sorts of colors depending on how old it is and what environment it formed in. The different colors indicate what their best magical application is. For example, blue light, which forms around clean bodies of water, is often used in water-related spells. Regardless of color, roaming lights strengthen one's inner light, thus strengthening one's eminent light.
White light is the base form of each color of roaming light. In this state it has no specific magical influence, but can still aid in general spell casting.
ID: A diagram showing some of the colors white light can turn into (does not show all of them).
ID: A picture of a spirit standing safely in dark rain thanks to the effect of blue light.
Even without using them in spells, having certain colors of light within your inner light can cause minor magical phenomena to happen. For example, having green light on your person may accelerate the growth of plants around you. Cyan light may make it easier (or harder) to fly.
Having more of a certain color may also strengthen the ambient effect. This can be seen during the Elemental Trials, where trial-goers are temporarily given powers like the ability to walk on water (with blue light) or the ability to vanquish monsters (with orange light).