I was never a fan of this ip, but I once dated someone in the early 2000s who was, and saw the first 4 movies I think. And obviously fantasy is fantasy, most of us know that "magic doesn't work like that" by pointing a wand and saying a single word to produce flashy lighting effects that cause reality bending results instantly.

But, it still bugged me, that we spent all this time in a magic school and never got taught an actual spell, with one exception (correct me if there are any other exceptions as i havent read the books or seen movies 6 through 80).

That exception being the patronus charm, which actually has all the "anatomy" of an actual spell, and is a pretty good one, in chaos magic terms we would call it a "protection servitor."

The servitor is visualized as having an animal form imbued with spiritual "flavor" of an ancestor spirit or protective deity. It is also good to tie the servitor to a physical object or body, which might be a wand, but could be a tool such as a knife more appropriate for banishing, or some other icon, idol or object that is reminiscent of the servitor's form or whatever, perhaps a shield or something.

The servitor is activated or called to action by combining the visualuzed component with verbal and somatic trigger words and gestures.

Literally gesturing with the wand and visualizing the elk or whatever while shouting "PATRONUS" It has material, visual, verbal, and gestural components, hitting most of your senses sight, hearing and two kinds of touch.

Of course you might want to change the animal symbol, or the activation words or gestures, or the physical representation of the spirit, but also, while creating it, you can do things like train it to perform the lesser banishing pentagram. For example, by using a dagger as the spirit's physical tether, you could perform the LBRP, instructing the servitor to learn it. Later, when performing an unrelated ritual, you could call upon you servitor to perform your pre and post ritual banishings in an instant, with a single word, thereby saving time and streamlining ritual performances.