Strixhaven coming up gave me the idea to make a Harry-potter campaign, but the rules of magic and spells are very different, so I was wondering if anybody had some homebrew spell mechanics or just homebrew spells for that setting. 

The sarcastic entity that lives in my head wants to ask if this is based on the books or the films.

If it's based on the books, then there's a wealth of spells which can be recreated for a purely magic based system.

If it's based on the films, every spell will have the same effect; the wand will go "ooOOooO" like a child loose in a gift shop that sells sliding whistles and the target will be blasted backwards. Rictusempra, expelliarmus, stupefy, erania exime, every one will make the want go "oo" and the target fall over. There's only a half dozen actual spells in the films, it sometimes seems. But that aside...

I'm not sure dnd is the best basis for a Harry Potter themed game. You could, however, run a similar themed game which uses dnd lore for the spells but a hogwarts style location, and limits players to spellcaster classes only. So lessons in how t oappease your god for clerics and paladins, how to pick your patron for warlocks (perhaps including work experience where they work for a patron for a week), non-violent spell options for wizards (or "how not to fireball"), wildshape lessons for druids, and so on.

The issue comes when you try to do the lessons. Wildshape lessons will be boring for a wizard player, for example, because they can't do it. You could run it that players start with one level in each class, so that they can participate in all of it, then perhaps reduce their hit dice and increase max level so that they are still able to get powerful as one class.

Also wizards in Harry potter are more like Sorcerers than Wizards. They don't carry spellbooks around to prep from, the magic is an ability they are born with, etc. The only wizardy aspect is that they can all learn the same spells.

So in short: doesn't translate well. 

Also you need to be concerned about "power" - because in Harry Potter there's minimal progress. Anyone of any age or newness can learn spells like the Forbidden Curses, and they can affect the world around them in major ways sometimes without even trying (and without even having a wand). 

HP and D&D are very different. I think it would better to just have "wizard's academy" trope rather than trying to make D&D magic work like HP magic - as that would be a massive headache and very confusing. 

Ok thanks guys