Alien Tongues

This spell prevents one humanoid you target from communicating ideas with its allies. Choose one humanoid that you can see within range. The target must succeed on a Charisma saving throw or be target to the spell. The target can't speak clearly for the duration, and when trying, only gibberish sounds leave its mouth. Only through telepathy or mindreading means can the target be understood. The humanoid doesn't know he is target of the spell until after the spell ends.

At higher levels: When you cast this spell using a spell slot of 3rd level or higher, you can target one additional humanoid for each spell slot above 2nd level. The humanoids must be within 30 feet of each other when you target them.