A way to burn things, a way to shock things, a way to freeze/chill things, and a way to melt things.

So, fire, electricity, anti-fire(cold), and acid/base/powerful solvent. 2x for utility vs. combat applications.

So that's 4 more minor and 4 more combat. Unless they're just different applications of the same fundamental thing.

A way to quickly decay things (iron bars, flesh) could be one each for each legal application you want or one spell with multiple legal targets.

Some spell that manipulates sound, either creating false sounds somewhere or mimicking voices heard previously or both. Another that uses it either to push or stun/damage enemies.

Ye olde sorcerous bolt of unspecified arcane energy...