Disguise Spell

 
Prerequisite(s): Perform 9+ ranks, Bardic Music
 
Benefit: You can cast spells unobtrusively, mingling verbal and somatic components into your performances. To disguise a spell, make a perform check as part of the action used to cast the spell. Onlookers must match or exceed your check result with a spot check to detect that you are casting a spell. Unless the spell visibly emanates from you, or observers have other ways of detecting it’s source, they don’t know where the effects came from.
 
Source: Complete Adventurer