pawsplay
Hero
Hypersmurf said:The rules say she can't cast Fireball at a caster level lower than 5th: the minimum level required for a wizard to cast fireball.
Not "the minimum level a wizard can choose to cast fireball", but "the minimum level required for a wizard to cast fireball".
-Hyp.
The minimum level required for a wizard to cast fireballs is 5th, the level at which they get 3rd level spells. Thus, they must choose to cast it at 5th or higher. However, fireball does not require a caster level of 5th. A caster must choose to cast it at 5th or higher.
I see nothing that indicates fireball fails to function at less than 5th level; it is simply impossible to choose to cast it at a lower level, because the rules for magic state that you must cast it at the minimum level. That is, at the minimum level for you to cast the spell. As you will note there is nothing in the spell description that states a fireball is a caster level 5th or higher spell; that information can be gleaned from reading the wizard class description. A sorcerer must cast the spell at 6th. A sorcerer cannot cast it at 5th, because he cannot cast 3rd level spells at 5th level. The fireball itself, however, does not care.