Tongue of madness was a fungus that grew in the Underdark. When mature, it resembled a large human tongue and was edible but somewhat poisonous. When consumed, any creature with the power of speech who did not have sufficient constitution to resist the mind-altering effects was compelled to speak his or her every thought for the next hour. This compulsion could be cured by a lesser restoration or similar spell.[1]


  1. Christopher Perkins, Adam Lee, Richard Whitters (September 1, 2015). Out of the Abyss. In Jeremy Crawford ed. (Wizards of the Coast), p. 23. ISBN 978-0-7869-6581-6.