Editing Yagura:SRD:Casting Spells (section)

=====Bonus Types=====

Usually, a bonus has a type that indicates how the spell grants the bonus. The important aspect of bonus types is that two bonuses of the same type don’t generally stack. With the exception of dodge bonuses, most circumstance bonuses, and racial bonuses, only the better bonus works (see Combining Magical Effects, below). The same principle applies to penalties—a character taking two or more penalties of the same type applies only the worst one.