I have an idea:
What if Magic spell effects would be more or less efficient depend of the day/night, place and weather?
ex)
Crystal way: better during day, bad when it\'s night
Dark: better during night, bad when it\'s day
Blue way: better when it\'s snowy, rainy or cold outside, bad when it\'s hot and dry
Red way: better when it\'s hot and dry, bad when it\'s snowy, rainy or cold
Azure way: better when the character is in the exterior world (azure way is air-oriented....), bad in interior places
Brown way: better when the character is in dungeon, caves or any other interior environments, bad in exterior world.
That dont mean light spell would be useless during day, for exemple, that just mean that it would be less efficient (let\'s say -50%) or it could cost more manas or both. This way, it would add very much to the mage characters\' strategies! We would see mainly dark mage at night in action

This idea could be apply to the monster too. Some monster could be stronger depending of those factors.