EzekielRaiden
Follower of the Way
Answering this question requires that we identify what elements produce "feel[ing] caster-y".So, there's once again discussion in a thread about how casters get too many slots to properly balance them for the adventuring day and while i don't want to focus on that specifically it sparked something to think about, if we wanted to move caster design away from being reliant on having a big ol' pile of spell slots to enable the casters to do their magical things and feel magical what abilities would we give them instead?
personally i think the paladin and the artificer are a good place to draw inspiration from because they have to try to 'feel magical' while only relying on halfcaster progression, as well as the warlock who already embodies this kind of slot-minimalism caster design, paladins have their lay-on-hands: healing which isn't dependent on slots, and their auras, always-on proximity buffs, artificers have their magical tinkering and their infusions, proxying their magic into objects instead.
so what kind of design would you choose to use if casters needed to be designed with their slots being less of their primary avenue of magic?
So--what does that feeling feel like? What visuals do you see when you're having that feeling? What actions can reliably pull it off? Are there spells that don't feel "caster-y" even when you are, in fact, casting them?
As a preliminary step, to make this something more than just reflecting a question back at you, something I do in my Dungeon World game, all people who can practice some form of magic have "magical senses". People without such training genuinely can't observe anything but the direct physical effects of spells and supernatural phenomena. Those who do get such training necessarily develop magical senses, because...I mean you need them in order to know that what you're doing is working. Each spellcasting tradition approaches these senses differently, and because it's a genuinely distinct sense, it has to be explained somewhat metaphorically.
I think this does a decent job of making the world feel like it has great magic hidden beneath the skin, that those who are trained can find and those who are not are blind to. That secrecy is very much part of not just Hermeticism, which is the soil from which the D&D Wizard grew, it's also part of things like mystery cults, vision rituals, and similar sorts of things. That gives a feeling of having the supernatural close, a breath away, being able to part the grass and feel the pulse of the Unseen World.
I'm sure there are more techniques, though, so it would help a lot to specify more about what it really means to feel "caster-y" in general. Then we can come up with concepts, mechanics, and structures that produce that feeling without needing to be driven by resource expenditure. Dreamscarred Press's Spheres of Power may also be worth checking out, as I personally find their approach fascinating and richly detailed while really cutting down on the obscene power that spellcasters can achieve. Spheres might then present a path forward for tweaking things so as to capture the "caster-y" feeling while avoiding power creep.