Complex sentence: After the match, Voldemort's followers attack the site, destroying spectators' tents and wreaking havoc, and the Dark Mark gets fired into the sky, which leads to a panic, as it is the first time the sign has been seen in 13 years.
Split into simpler sentences: After the match, Voldemort's followers attack the site, destroying spectators' tents and wreaking havoc. The Dark Mark gets fired into the sky, which leads to a panic since it is the first time the sign has been seen in 13 years.