Evasive Maneuvers

 
Prerequisite(s): Cunning Evasion, Spell Focus (Illusion), Caster level 11+, ability to cast invisibility.
 
Benefit: Once per encounter, if you are caught within an area attack whose damage you completely avoid due to evasion or improved evasion, you can cast a prepared or known invisibility spell as an immediate action.
 
Source: Exemplars of Evil