I integrate "Light" & "Dark", or as I call them in my game "Holy" & "Chaos", into my world's overall mythology, & magical theory.
Specifically "Elements" as they pertain to magic are divided into three trinities.
Earth (solid), Wind (gas), Water (liquid), magics are magics that alter the natural world through manipulating these naturally present materials in the environment, & directing them to a purpose. Simply put, magic is being used to manipulate matter through directed control, of the matter itself. Think Avatar's bending without the martial arts moves.
Fire (combustion), Frost (cryogenics), & Lightning (conduction) represent alteration of the matter via magic that is being used to create a point of concentrated process. I.e. instead of manipulating "lightning", "fire", or "Ice"; magic is used to generate the processes that create those effects within a limited area.
The first two trinities represent natural processes of the physical world being manipulated through mana.
The final trinity "Holy", "Chaos", & "Spirit" are actually manifestations of Order, Entropy, & Balance; & are of course "Supernatural Principles" rather than natural processes. They are of course tied to the various deity pantheons that embody their respective essences. Are naturally antagonistic towards each other on an inherent level, & in the case of order & entropy entirely antithetical to each other. & when matter of the physical world is exposed to their currents, it warps them.
I.e. "Order" restores the natural state of what it touches & thus manifests as healing magic, as well as being anathema to the undead, but can cause damage if improperly applied. "Entropy" causes corruption, mutation, blight, & reanimation of dead flesh into undead creatures. While finally "balance", acts as a force of grounding & negation, against the manipulating currents of magic.
The effects of the final trinity are widespread for in game lore reasons, having to do with an already occured cataclysm, that "opened wide the floodgates" metaphorically speaking, & thus rather severely altered the world from its original state. Thus creating monsters, demi-humans, & undead; as well as empowering people with the ability to manipulate the world through magic.