Here's how I modified your great feat idea.
Wormtongue (feat)
By making a successful Bluff check you may conceal a spell's verbal components within normal nonmagical speech without allowing anyone to notice. The Bluff check is opposed by anyone able to listen to the conversation by making a Sense Motive roll. Each 5 ranks in Spellcraft grant a +1 circumstance bonus to the caster and/or the listener.
Wormtongue (feat)
By making a successful Bluff check you may conceal a spell's verbal components within normal nonmagical speech without allowing anyone to notice. The Bluff check is opposed by anyone able to listen to the conversation by making a Sense Motive roll. Each 5 ranks in Spellcraft grant a +1 circumstance bonus to the caster and/or the listener.
