I took a break from the hobby, and returning I am kinda saddened to see what has befall it. So I am working on my own setting with modified OSR rules. I am particularly loving the Lion and Dragon and Baptism of Fire rules but want a slightly more traditional approach to magic, kinda. I want there to be magic, but just 1 caster class at all, and all schools of magic are lumped together, IE Arcane, Divine, Primal, etc etc. So far this is what I have come up with, and would appreciate some feedback on it. Mainly if anyone seeing issues that would crop up as game play progresses, I've never been a "mechanically" inclined DM.

GRIMOIRE CASTING
-A caster must have their spell book in hand to cast any spell from it.
-Spell books are bulky and fragile and going into combat with one is risky, but necessary.
-Losing or heavily damaging a spell book will all  but make it useless to the caster.
-The spells must be prepared ahead of time from the book to be cast.
-Prep time is 1 turn per spell level of said spell, per spell, which makes this prep time a major thing for casters, it's no simple quick rest.
- Once prepared from the book, the spell is set to be cast, and must be done so with a caster check, a d20 + caster level + Int modifier VS a difficulty of 10 + spell level. On a success, it is cast, on a failure, the caster must make a save VS the backlash and cannot attempt to cast that spell for a number of rounds equal to it's spell level. On a failed save, the spell is unable to be cast till it is prepared again.

Now as far as the spells that available to the players, I am still working on that, as there is magic in this setting but most people in the world to not have PC class levels, but NPC class levels, with those having PC class levels rare or powerful people not much above 5th level currently.