Other people have written about one possible limitation for Magic Users in the reading of the B/X Rules: magic users and elves may only know as many spells as they are able to cast per day. Their spell book just cannot grow beyond this limit. I will still let magic users and elves start with two first level spells and one second level spell, however.
I’ll give the above limitation a try in the Labyrinth Lord campaign we’re running in the first half of 2011. We’ll see what the players think of it.
I’ve started to make a list of 9th level magic users (many of them inspired by magic users played by myself and others in different games in recent years) and assigned them their spell book according to the limitations discussed above: three first level spells, three second level spells, three third level spells, two fourth level spells, and a fifth level spell.
Learning about the spells at the disposal of the various magic users in the setting, searching them out and learning their spells is going to be an important element of gaining a level. Essentially these magic users are the magic schools available for player characters.
The campaign starts out near a settlement of elves sailing the sea ruled by their queen Gerdana. Her spells basically define the standard spells available to regular magic users in the area.
I’ve also tried to go through the collection of spells I gathered from the Ancient Vaults & Eldritch Secrets blog, assigning these spells to the various 9th level magic users of the setting. That’s how I’ll introduce new spells. We’ll see how well this goes.