Transmutation [Sonic]
Level: Bard 1
Components: V, S
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Target: One creature
Duration: 1 round/level
Saving Throw: Fortitude negates
Spell Resistance: Yes
By pointing and making a number of loud, nonsensical sounds you release the power of the spell. The target attempts to speak, but spews forth only gibberish instead.
For the duration of this spell, the subject has a 50% chance to miscast spells that have verbal components, and any time the subject speaks (including the use of magic items activated by command words), there is a 50% chance that the utterance is completely incomprehensible and therefore ineffective.
Source: Spell Compendium, page 69. Originally published in Complete Adventurer, page 145.