>>150775179
The gist of what you need to know:
Following the Magic Wars, Earth elects a Margaret Thatcher type politician Earthgov President. But she's in league with the Dominators, who want to conquer Earth on the downlow. Not-Thatcher is anti-Legion and starts stirring shit up against them, as Earth and pretty much the entire United Planets got wrecked by the Magic Wars turning off just about all technology for several months.
Garth and Imra's kid who was Validus turns out to have a disease that kills everyone who is of his parents species and has to be put in a containment suit/sent to live in a medical space station where the Legion meet Kent Shakespeare, who basically is a replacement for the dead Mon-El for the team.
Laura Grand, a descendant of Mon-El and who Brainiac 5 once loved, marries Rond Vidar and has his child.
Khunds start invading planets and declaring war on the weakened United Planets. Duo Damsel and Bouncing Boy take the Legion Academy kids and form a militia to protect worlds that are being invaded.
White Witch marries Mordru and restores his full power so he can protect the newly colonized Sorcerer's World 2.0 from the Khunds. Mordru becomes king of the planet and evil again, turns the midget sorcerer Khund who is Mysa's best friend into a soulless vampire with no face, and starts to physically and emotionally beat Mysa until he's pretty much broken her into being a helpless wreck. Adding to this, Mordru imprisons and tortures Rond Vidar when Mysa calls him to help her escape the marriage.