Answer:
Type of figurative language: hyperbole, the "illegal" in parenthesis shows that it may be a bit of an exaggeration to say it was illegal.
Meaning of figurative language: Hyperbole is extravagant, intentional exaggeration. “I have a million things to do today” is a common example of hyperbole.
Effect on tone or mood: It dims the mood to a more serious tone by using the exaggeration of the hyperbole. To say something is illegal is different then just saying it is against the rules. The choice of words is very effective at this point
Effect on audience: Using that term lets the audience know that it is a serious matter that the characters are dealing with. And is to be taken seriously.
(sorry if I answered it wrong, I didn't quite understand what was being asked)
Have a great day!! :)