Magic

Magic flows throughout the entire world of Byd, as a natural force, and as a material. It flows in from the other planes of existance through specific weak points in the fabric of the world, and flows out in other weak points, and while it travels in straight lines between these points, it suffuses the entire world.
The flow of magic across the world waxes and wanes. Different kinds of magical energy are strongest and weakest at different times, for example Illusory magic is strongest at the full or new moon, while Transmutation is strongest in a waxing or waning moon. Divination is strongest on specific days. Necromancy is strongest at night, while Evocation is strongest in the day. While these effects do not matter much for minor users, if high level magic user wishes to get the most out of their magic, they should perform it at the optimal time, and in an optimal location.
The magic of the world can be directed by those with The Spark, but many creatures can tap into it incidentally to fuel their growth or existance, like the Mountain Silkworm.
This all applies for arcane magic, divine magic comes from a god or force of nature infusing the creatures spark with magic from their own reserve. This magic comes from its worshipers though.

Manifestation

Some rare Sparked people are born with "The Sight" which allows them to see this flow and the concentration of magic around their environment. They see this through special cones in their eyes, which leads to it being described as another colour, named octarine.

Localization

The laylines that connect the inlets and outlets of the magical flow are incredibly straight, boring through mountains, but they follow the curve of the earth. However, this magic tends to diffuse through the world, so while it may be strongest on those lines, everywhere has a little bit of magical energy, except some very remote areas far from magical sources.

Type

Metaphysical, Arcane