My OSR-compatible rules for wizards can be found right. . .
They include the Illusionist, Necromancer, and Orthodox Wizard (the most traditional one).
I think these wizard rules are cooler than a witch's tit and hotter than a witch's other tit, but if you aren't interested is wading through another homebrew in search of bits to steal, here are the parts that I think are the most hackable:
- I think the whole spell slots + casting dice is pretty elegant. It removes the whole quadratic wizard thing and gives players a clear idea of how much spellpower they have and are bringing to bear. (I actually give them aluminum casting dice at the start of each in-game day. It's very tangible.)
- Book Casting is a great ability. It actually makes wizards feel more like wizards, since they're wading into combat with their big dorky spellbooks out, chanting stuff.
- Vancian Preparation would be good to port into a 5e game, except maybe give a different benefit. Maybe +1 to the spell slot, can only be used 1/day.
- Giving mono-class bonuses is a great fucking idea and I'm sad I didn't hit on it sooner. Just: I think it's a good idea to incentivize the all-wizard party or the all-thief party. It makes the game experience more diverse, gives us more ways to play the game.
- You'll notice that a lot of the old-school spells are a lot more powerful, and a lot more hackable. A lot of them have multiple uses. I tried to make spells like feather(fall), floating disk, lock, and levitate more comparable to sleep on the scale of usefulness.
- Also check out the Illusionist's Final Doom where they turn into an illusion and get stuck there. There's enough there for a blog post on its own.
- I tried to give a lot of diversity in the undead that low-level necromancers can raise. They all have different functions, and the necromancer's corpse economy means that they'll have to pick their favorite.