Philter of Stammering and Stuttering: When this liquid is consumed, it will seem to be beneficial—philter of glibness or persuasiveness, for instance. However, whenever a meaningful utterance must be spoken (the verbal component of a spell, the text of a scroll, negotiation with a monster, etc.), the potion's true effect is revealed—nothing can be said properly, and the reactions of all creatures hearing such nonsense will be at a –5 penalty.
Encyclopedia Magica[]
When this liquid is first consumed, it seems to be beneficial, a philter of glibness or persuasiveness, perhaps. However, whenever a meaningful utterance must be spoken (the verbal component of a spell, the text of a scroll, negotiation with a monster, etc.), the philter's true effect is revealed nothing can be said properly, and the reactions of all creatures hearing such nonsense are at a -5 penalty.
This philter functions as a philter of glibness or persuasiveness when imbibed by a Jester (a bard kit) and has no ill effects.