Needs review
Source: Encyclopedia Arcane: Illusionism

Description: You have gained mastery over the use of one form of Illusionism

Prerequisites: Spell Focus (Illusion)

You add a +5 bonus to the Difficulty class for all saving throws against spells versus one kind of the following types of illusion: figment, glamour, pattern, phantasm. This does not stack with Spell Focus

Special

You can take this feat multiple times. It's effects do not stack. Each time you take it it applies to a different type of illusion.