+++Warning, this contains very minor season two spoilers, but no major spoilers from season three+++
Season three of Legends aired in the 2017-2018 TV season and is again a mix of a monster/demon/"weird thing"-of-the-week procedural and a serial with a Big Bad that the group has to deal with by the end of the season. This season, the big bad is a demon named Mallus (voiced by John Noble) who was released when the Legends tried to travel through time with two versions of themselves at the end of season two. This also created anomalies called anachronisms, which are basically people or objects displaced in history. Rip (Arthur Darvill) has created a Time Bureau to replace the time masters to hunt down the anachronisms and try to restore the timeline, forcing the Legends to retire. Of course, they do not stay retired, and the usual shenanigans of the show ensue. Eight episodes into the season we get the big crossover event, Crisis on Earth-X (which includes episodes of Supergirl, Flash, and Arrow), of which the Legends installment is the final one. The crossover has major implications for all of the shows, including Legends.
For those who get the Blu-Ray set, the release is pretty much on par with the prior season releases, both in terms of A/V quality and bonus features. The extras include all of the episodes of the crossovers from the other shows, so you can watch in total without having to get the discs from the other shows, deleted scenes, and a gag reel. Then there is a featurette specifically on the crossover event and a best of DC TV at Comic-Con, both of which were released on all of the DC show's DVD and Blu-Ray releases that year.
Overall, the season is good, both in still developing the existing cast members and introducing new cast members, some of whom would eventually become series regulars. Those include Jess Macallan, who plays Ava Sharp, a member of the Time Bureau, who can't stand the Legends, Adam Tsekman, who plays Gary Green, a member of the Time Bureau who loves the Legends, Courtney Ford (Brandon Routh's wife), who plays Nora Dhark, the daughter of Damien Dhark, and Matt Ryan, who reprises his role as John Constantine, who was brought into the Arroverse during one of the flashback sequences on Arrow. The show continues to be the more offbeat of the Arrowverse shows and can get downright silly (especially in the season finale, when the silliest thing the show has ever done is pulled off). That said, it works for the show, and the actors seem to have a lot of fun with the material, and with each other. So, if you have liked the more offbeat nature of the show in the first couple of seasons (especially in season 2), this is definitely worth watching.