I've been thinking about my "Spell System Overhaul" and realized that it did not sit well with me. For one, it places too much emphasis on ability scores. Also, I think the spell bonuses are too high - more akin to AD&D than OD&D. And I think it's worth keeping the goal in mind of having more useful low-level spell-casters. So I think a simpler solution is this:
- MUs or Clerics with a prime requisite of 13 or more get a bonus 1st level spell.
- MUs or Clerics can store one spell in a staff, wand or holy symbol.
I think it is still worthwhile to not allow MUs to memorize duplicate spells, to encourage variety, and to allow read magic as an additional spell each day. MUs can be provided with a study scroll of all 1st level spells, but must find, buy or research spells of higher level.
OD&D Clerics have such small spell lists, I think it makes sense to still allow them to free-cast and have access to all the spells of a level they can cast. Clerics can also use a book or study scroll if the referee desires, or the spell slots can just be granted divinely each day.
Just thinking about how this would play in practice, Murray the Mage has an above-average intelligence (14), and so at 1st level gets a bonus 1st level spell. He is not allowed to memorize duplicates, but he has access to a study scroll of all 1st level spells provided to him by his mentor. The day he plans to go on an adventure, he memorizes charm person and hold portal. He also imbues his oaken staff with the magical energies needed to cast a sleep spell, and finally he has read magic memorized.
So this gives Murray a decent variety of spells - one utility, two offensive, and one defensive spell. Because the bonus is just one 1st level spell, this baseline set of spells doesn't change - at subsequent levels he just adds spells as per the normal advancement chart. If nothing else this makes him much more useful at low levels, and the staff also gives him a slight boost at higher levels.
Murray's companion Lana the 1st level Cleric is not as wise as her peers (10 WIS), but she can still prepare her holy symbol with the divine energy needed to aid her undead turning attempts. If she had a WIS of 13 or more, or was 2nd level, she could instead choose to store a 1st level Clerical spell in her holy symbol. Also with a WIS of 13 or more, she could cast any one 1st level spell as needed each day, independent of how she had prepared her holy symbol.