Fumbletongue

This enchantment causes a creature to be unable to speak intelligibly. Any effort the target makes to talk, in any language, comes out as a useless mix of unconnected words and noises. Even magic words are affected to some extent; the target has a 20% spell failure chance for any spell it attempts to cast with verbal components, and a 20% chance to incorrectly use a command word to activate a magic item. This spell has no effect on telepathic communication, or the vocalizations of creatures that lack a spoken language.