Early update from Comics Continuum today. The "destroyer of galaxies" that was announced earlier will not be Darkseid. It will be Imperiex. For those who don't know who he is, Imperiex was introduced in the Our Worlds at War event held by DC in 2000. He is described as "The Devourer of Galaxies, the embodiment of entropy, signaling the end of existence". The rest of the Legion news from CC:

• "I wrote a Timber Wolf story and I think there will be more to do when I get back to New York," DeMatteis told The Continuum during an appearance on Sunday with Abadazad collaborator Mike Ploog at the Los Angeles Comic Book and Science Fiction Convention.
  "I was surprised. It was actually a pretty intense episode."
  DeMatteis said the second season will see "a shift in focus."
• Imperiex will likely appear starting with the second-season debut.
• The Superman seen in Season 2 will not be the same Superman as seen in Season 1.
• The Fatal Five will be returning next season.