Hey! Loved the premise and mechanics. My personal favorite magic rn is Umbral Void due to the contrast with Pythea (Light Manipulation)
With that said I have a few suggestions based on my experience:
Some spells few a bit useless or just not worth it currently. For example in the Umbral category you have spells like Umbral Slip which guarantee you a dodge on the next action. This may sound useful on the surface but it means you're likely taking damage on that turn, to then maybe dodge when you're casting a spell on the next turn. It's vastly preferable, mana-wise, to either evade that turn or the next, since you've got a great chance to dodge the coming attack anyway.
Likewise some of the "damage dealer" options in the Maleficar and Chaos categories feel underwhelming in how much damage they deal and accuracy. Considering some of these have no stun options, you would think they would compensate on DPS/Bleed effect.
I also think the prologue needs a little more time to cook, we have too little information on the characters and especially Thaddien considering he dies pretty much a while after he's introduced. Also Pythea's hate feels a little overwhelming? Like I get she's ambitious but did we kill her dog or something for her to act like that lol