@Sir Canadian Rhythm Senpai: An idea I had - maybe Arcanist skills scale with how much AP you have stored up when you cast the spell or some other factor like a status effect that stacks when you do something, like building up "Stacks" per cast to make things stronger. Maybe magic missile fires 1 missile per 1 ap or stacks you have when you cast it. In World of Warcraft arcane mages have a simular system, "Arcane Charges". They can store up to 4, and all their stuff is stronger when they have more - but more expensive. Lower charges, lower damage, but less cost. In this sense, Arcane Inisight could give you a free stacks instantly (At a cooldown) and a small damage buff. Like "Oh I need 4 stacks RIGHT NOW", get 4 stacks instantly (5-6 round cooldown?), but when you cast magic missile, its +4 missiles.

Also, arcane mages can easily control how many charges (and mana) they have, using abilities to instantly restore them or gain multiple charges quickly (ableit with a cooldown). Mana in this sense would be +AP cost to spells, and -AP cost to spells.

I know that the bard and monk class mods have systems like "Devour this many status effects on ally/enemy, this skill does more when it consumes 3/5+ buffs" and a combo point/finisher move system. Perhaps copying a mechanic like theirs?

Some ideas;

New Status: Arcane Empowerment

Effect: This status stacks up to 5 times. Each stack gives +25% spell damage and +1 AP cost to all spells. They last for up to 2 rounds (applying a new stack refreshs this duration).

Arcane Insight (0 AP Cost, 6 Round Cooldown), You gain 4 stacks of Arcane Empowerment immediately. Your AP costs for all spells are reduced by 2 for 2 rounds (So net of +2 AP Cost, not +4, for 2 rounds).

Magic Missile (0 AP Cost, 1 Round Cooldown), You fire one missile at long range that deals X damage/type. Your level/intelligence determines its damage. You fire an additional missile per stack of arcane empowerment you possess.

Arcanist's Channeling (0 AP Cost, Stance - Turn Off/On, infinite duration), while channeling is active, you gain 1 stack of arcane empowerment each time you cast a spell, up to a maximum of 5.

Power Word: Shatter (1 Ap Cost, 4 Round Cooldon), select a target in long range that is frozen or petrified. You instantly kill them if they have 25% or less vitality. For each point of arcane empowerment you posses, the threshold to kill the target is increased by 5% (to a maximum of 50% hp or less).

Discharge (0 Ap Cost, 1 Round Cooldown), you can vent your overwhelming energy, dealing area damage around yourself and knocking enemies back. Deals more damage and has a larger area per point of arcane empowerment you possess. You lose all stacks of arcane empowerment after casting this spell.

Arcane Fury (1 Ap Cost, Self Buff, 3 rounds duration, 1 round cooldown) Your weapon gains a small bonus magic damage equal to the number of arcane empowerment stacks you possess. You gain one stack each time you attack or use a weapon skill.

Blink (1 Ap Cost, 4 Round Cooldown) You teleport a moderate distance. You can activate this skill again within the next 2 turns to return to the location you teleported from. This skill is unaffected by arcane empowerment.

Etc, etc. Just a general idea. Whatcha think?