The series, set in the shared Marvel Universe, is part of the wider X-Men line and a Sequel Series to the ongoing New Mutants comic, which ended a couple of months earlier. It's part of Destiny of X, the third phase of the X-Men franchise's long-running Krakoan Age saga.
The original 1983 New Mutants series introduced the team as junior students at Professor Xavier's school. Whereas the X-Men were superheroes, the New Mutants were teenagers, most of whom were still trying to accept and control their mutant powers. But that was a long time ago - nowadays, as shown in the most recent New Mutants series, the remaining members of the original team are older, wiser and living on the mutant island of Krakoa, acting as mentors to a whole new set of teenage mutants.
The final arc of that series ended with new character Escapade joining the team, who were then captured by human extremists the U-Men, a cult of Fantastic Racists who seek to upgrade themselves to superhumans by using mutant bodies for transplants and grafts. They managed to escape and defeat the U-Men, but the new series starts by revisiting some of that unfinished business...
New Mutants: Lethal Legion contains examples of the following tropes:
- Absurdly Spacious Sewer: Wolfsbane and Morgan Red take a wander through New York's sewers. They're spacious, reasonably well lit by light coming through grates, and have plenty of dry platforms to stand on. They're also home to a huge, mutated alligator and a secret lab (which apparently belongs to Spencer Smythe, the villain behind the original Spider-Slayer).
- Batman Cold Open: The first issue begins with Escapade, Karma, Wolfsbane, Cerebella and Mirage defeating another squad of U-Men and freeing their prisoners. The aftermath shows Cerebella still feeling miserable despite their success and Escapade trying to help her, which leads into the main plot...
- The Bus Came Back:
- Psi-Borg, or a legacy character using the name, appears for the first time since her 1993 appearance in Nick Fury, Agent of S.H.I.E.L.D., as one of Nefaria's recruits.
- Eclecta is back for the first time since her Deadpool debut in 2000.
- Sweet William returns for the first time since his 1970 debut in The Avengers
- Volga Belle is back for the first time since the 2009 Hulk: Winter Guard one-shot.
- Call-Back: The secret lab Wolfsbane and Morgan Red find in the sewers belonged to Spencer Smythe, the scientist behind the first version of Spider-Man's robot adversary the Spider-Slayer. They eventually reactivate one of his old robots.
- Continuity Nod: While running from a monster in the sewers, Wolfsbane and Morgan end up at the site of the Mutant Massacre.
- Covers Always Lie: The first issue's cover shows versions of two classic New Mutants villains, the Demon Bear and the Shadow King. Neither appears, or is even mentioned, inside the comic.
- Establishing Character Moment: Count Lucchino Nefaria first appears in his mansion, standing in front of a huge portrait of himself and wearing an old-fashioned suit, a waistcoat, a cape and a monocle. He plays a vinyl record (implied to be opera or classical, given its sleeve) and fills his wineglass from a decanter. He laments the fact that people have forgotten to be afraid of him these days. And then he brutally executes an intruder who's tied to a chair. All of which establishes that he's an old-fashioned card carrying villain... but a genuinely dangerous one.
- Fights Like a Normal: Escapade uses her Swap Teleportation tactically in combat, but she relies on stolen weapons or a short range taser to subdue foes.
- Sad-Times Montage: When Cerebella's talking to Escapade in the first issue, trying to work out why she still feels down after the team's victory over the U-Men, she wishes she could take the montage option.Cerebella: I'm sorry. I'm being boring. I wish I could just montage this @#$%.
- Sewer Gator: Morgan Red and Wolfsbane encounter a huge, mutated alligator in the Absurdly Spacious Sewers of New York. It's not friendly.
- Swap Teleportation: Escapade's power allows her to temporarily swap with another person - the simplest version of this is a purely physical teleport switch. During the Batman Cold Open she uses this to rapidly swap positions with several U-Men, sometimes acquiring their armour and weapons when she swaps.
- Who Wants to Live Forever?: Morgan expresses this sentiment, as he equates the ability to keep returning from the dead only to fight for survival until your inevitable death and rebirth as no different from Hell.
