Programmed Illusion

This spell functions like advanced illusion, except that this spell activates when a specific condition occurs. The caster sets the triggering condition when casting the spell. The event that triggers the illusion can be as general or as specific and detailed as desired, but must be based on an audible, tactile, olfactory, or visual trigger. The trigger cannot be based on some quality not normally obvious to the senses, such as religious belief or magical ability. For example, the spell could be set to trigger when a character wearing robes and a pointed hat enters an area, but not when a Magic-User enters the area. The spell remains ready indefinitely. When triggered, the spell will last at most 1 round per caster level.