Following the departure of Superboy, the series continued without him as the series reached an important crossroads with the collaboration of Paul Levitz and Keith Giffen, both of whom would have a long relationship with the series. With the Great Darkness Saga, they introduced Darkseid into the 30th century.
The series was retitles Tales of the Legion of Super-Heroes and simultaneously relaunched. The new series briefly featured original stories before publishing reprints.
Legion of Super-Heroes: The Great Darkness Saga - Deluxe Edition
Legion of Super-Heroes (Vol. 2) #284-296, Annual #1
Legion of Super-Heroes: The Curse - Deluxe Edition
Legion of Super-Heroes (Vol. 2) #297-313