I'm having a bit of trouble understanding something fairly.. elementary.
Many spells, invocations, etc. say that, in order for the target to survive or negate part of the effects, he must make a fortitude/will/reflex save. Sometimes the nature of the DC is explained, for example 1/2 caster level + wisdom modifier, or something similar.
Most of the time it is not. When the description simply says "enemy must make a will save, or become <effect>" and nothing else, what should I assume about the DC of this save? Is it Caster level? Caster's own will/fortitude/reflex? Charisma/Int/Dex/Wisdom modifier?