Complex sentence: Foaly argues against the idea, but due to Artemis' lying to Holly, saying that she infected Angeline with Spelltropy, Holly agrees to help Artemis immediately to make up for it, and Foaly had to give in.
Split into simpler sentences: Foaly argues against the idea, but due to Artemis' lying to Holly, saying that she infected Angeline with Spelltropy. Holly agreed to help Artemis immediately to make up for it, and Foaly had to give in.