Legion of Super-Heroes. The great darkness saga

This is Earth in the 30th century. A world of science and technology. A world of peace and light. Preserving this peace is the Legion of Super-Heroes, a group of young adventurers who are the best and brightest of their kind. But a darkness is approaching their world. A centuries-old evil that threatens to destroy their entire universe. Herein lies the story of the Legion's greatest challenge, complete in one volume.