Tongue of Babel

A target creature you can see within range must make a Charisma saving throw. On failure, for the duration of the spell, that creature cannot understand any languages it would have otherwise known, including telepathy and other means of communication. For the target, spoken words sound foreign, and writings look like they were written in an unknown script.

At higher levels, the number of creatures affected is increased to 3 * the spell slot level + 1.