You can appear to be casting a different spell than your truly are.
Benefit: You may make a Bluff check when spellcasting to fool observers into thinking you are casting a different spell. Your check is opposed by the Spellcraft check of each observer. (If the spell has a casting time of more than 1 full round, observers may make Spellcraft checks once a round to correctly identify your spellcasting.) If you attempt to Spell Bluff with a spell that has a material component or a focus, you suffer a –5 penalty to your Bluff check. You select what spell those failing their Spellcraft check believe you are casting. If this is not a spell you are actually able to cast, you take a –5 penalty to your Bluff check. These penalties are cumulative. The effects of your spell may reveal your deception once it has been fully cast, but not until after it is too late for a foe to counterspell.
Adventurer’s Handbook: Genius Guide Volume 1