You cast a spell that you know or have prepared, following the rules for that spell. Make a spellcasting roll using the attribute specified by your Class. The result determines the degree of success and any associated Good or Bad Things.
Complete Success: The spell is cast properly, and you may select a Good Thing from your Class or the spell.
Success: The spell is cast properly.
Partial Success: The spell takes effect, but something goes wrong. You must select a Bad Thing from your Class or the spell.
Failure: The spell does not take effect.
Complete Failure: The spell does not take effect, and you have managed to do something wrong in the process of trying to cast it. You must select a Bad Thing from your Class or the spell.
The effects of a spell, including its Good and Bad Things, depend on the spell and your Class.