The target of this spell must succeed a CHA saving throw. On a successful save, the target spends it's next bonus action throwing up a large worm. On a failed save, the target's tongue transforms into a worm. Immediately upon transformation, the target looses the ability to speak. 

While effected by the spell the worm will bite the inside of the target's mouth, dealing 1d4 damage to the effected creature at the start of each of it's turns. 

If the caster maintains concentration for the full duration of the spell, the worm stops attacking the victim and becomes docile. The target looses the ability to speak for the next 1d4 days. If concentration is broken, all effects of the spell immediately end. A creature who has lost the ability to speak can regain it through a Dispell Magic or a Remove Curse spell.