CapnZapp
Legend
Well, I don't think taking this generic route will be fruitful. Either a sweeping benefit will be too strong (in the strongest cases) or it will be too weak.Why not post the principles that you are wanting to apply? For example:
If you cast a spell of your specialist school:
- If it requires you to make an attack roll, you get advantage.
- If it requires the target to make a saving throw, you add +5 to your spell DC
- Otherwise, it counts as if you had used a spell slot one level higher
That sort of thing. Not saying those are the rules you have in mind, but tell us what yours would be.
Lanliss is clearly thinking of creating school-based benefits individually for each spell. While that is more laborious, it is also the only way that can tread the narrow path.
As for the "that's a huge undertaking" argument, nothing says he can't do the spells one at a time...