Where Merlin reached Arthur and Mordred just before Mordred fatally struck Arthur, and intervened. This is what happens next.

A training exercise gone wrong. Batman has the team practise with inhibitor collars incase they are ever in a situation where they are unable to use their powers... however things take a rather unexpected turn for the worst when villains attack. (original six only)

The Light, though the heroes don't know that it's them, have developed a ray that makes anyone who steps into it 10 years younger. Originally, it was meant to revitalise the near-middle-aged members of the Light to make them young and strong again, but then they had the idea that since the team is made up of teenagers, it would set back the heroes greatly if their sidekicks were hit by it and made infants and children. This is set in the first season, with only the original six members. (Robin is 13, Kid Flash and Artemis are 15, M'Gann and Superboy look 16, and Aqualad is 17)