Magic system for a game focused on apprentice wizards.

[LibraryOgre]

Until 4, I was going to say Ars Magica, and I still think you should consider it, for several reasons.

1) 4th edition's core book is free, so you might as well own it. (Looks like you need to sign up for their newsletter, these days; 5th edition is at Drivethru)

2) Varying skill levels for verbs and nouns, letting you emphasize certain people being better at some things... in Diane Duane's Young Wizards series, Kit is especially good with machines, while Nita has more facility with living things. If you drag a bit more Ars Magica in, you can also wind up with bonuses outside of the standard verb-noun... you might be really good in one place, or affecting red-heads, or when not standing on the ground.

3) Learning a formulaic spell is loads better than spontaneous magic, but you can try really basic things without knowing a spell. If you have that as a known spell, a level 1 Creo Ignem (create fire) is practically free.... if you're not stressed, roll d10+Creo+Ignem+Stamina, and get a 1 or better. If you're stressed, you will fail on a 0. If you have to do it spontaneously, it's d10+Creo+Ignem+Int, then divide by 5 (normal) or 2 (if you are willing to fatigue yourself); if you're stressed, or if you spent a fatigue level, you might botch on a 0.

This lets you have characters do things they know relatively easily, but also try out new things, especially in their specialties.

Also: The XP system is built around Seasons. You pick up things just by exposure, but also have stuff you study and get better at on purpose.