Warning: Lots of nonsensical questions.
Firstly, magic circles. According to the lore doc, “Magic circles are created to shape magic energy into an element or other kind of form in order to carry out the caster’s intent”, so would it be possible to harness “unshaped” magic energy without the use of a magic circle? What would this look like? Mizeria (mentioned in Shieldguard) seems to strangle her victims with “magic energy” as opposed to any mentioned type of magic, so does this indicate you can still project intent upon unrefined magic? What are the properties of unrefined magic?
Are there known limits as to where a magic circle can manifest? For example, Jujutsu Kaisen forbids techniques from being activated within one’s innate domain which encompasses their body. Would something similar be the case for magic? If not, what’s stopping a mage from summoning a placed explosion of metal or fire within an opponent’s body? There must be something that protects against it, or else fights between mages would be a race to see who can conjure a ball of their magic in the opponent’s skull first.
Is there a minimum or maximum size for a magic circle? It’s hard to imagine that a powerful enough mage could blot out the sky with a magic circle, so there has to be SOME theoretical limit. The opposite is true - a magic circle that’s barely bigger than a molecule wouldn’t be feasible to keep focus on, so where would the limits begin and end? The size of a nail? Of a finger? A palm?
How much can magic accomplish without needing a magic circle? Trace magic is already capable of creating a metal coating around your legs, making you invisible, and shielding you from explosions. Could a mage create tangible illusions based off previous people their opponent has fought that fight for them?
If fighting styles can only tap into trace magic, surely mages with full access would be able to use it in far more novel ways. Why would they remain relatively stagnant with their applications of magic, opting for traditional uses instead of the many unique possibilities they have at their disposal? Could a mage potentially mess with someone’s perception of time, slowing their mind to the point they’re unable to properly defend themselves?
Are there limits to what an enchanted item could do? Beyond the simple bonuses or mind protection, could it perhaps work in the opposite way? Would an enchanted (or cursed, I suppose) mask be able to slowly brainwash it’s wearer, or at least negatively impact their mind?
But most importantly, why can’t a mage change the color they intend their magic to be? Are you born with both the magic and it’s color preassigned, or is it something the mage simply chooses? From my understanding, it makes more sense for the element and properties of the magic to be predetermined, as color would certainly be more variable.