Illithids and Their Language

Mind flayers, and other naturally psionic critters with telepathy as their primary speech, have to learn spoken language as their second language.

Those that don't know a second language 'speak' in images, memories, emotions, concepts, whatever. Those that do can speak in more abstract terms, using words and pictographs.

There are psychics that posit that learning these other languages, especially too young, can affect them. Limit them. The limits of their language are the limits of their world. Some psychics are vehemently against this. Others think that more frequent interaction with limited forms is broadening and interesting, and should be embraced.

As a note: instead of "telepathy 120 ft." use a level dependent variation or 100 + 5d10 or something to represent variety in strength.