WARNING: The following contains spoilers for X-Force #1, from Ed Brisson, Juan Ramirez, Brian Reber and VC's Cory Petit, on sale now.
In superhero stories, it's a known rule heroes (usually) don't kill. Thus, when Zack Snyder's Man of Steel hit theaters, longtime fans of the hero raged when Superman broke Zod's neck. We've also seen the debate come up with regard to Christian Bale's Batman and Jason Momoa's Aquaman both consciously choosing not to save terrorists, a move that feels like indirectly killing them via an avoidable death sentence.
Semantics aside, however, it's generally accepted that a true hero ensures no one (whether an innocent bystander or the criminals themselves) dies, even if by accident. You have to pay meticulous attention to your surroundings and preserve life, at all costs. Well, one X-Man clearly didn't get the memo, and as of X-Force #1, due to negligence, the fan-favorite mutant Boom Boom has become a mass murderer.
Boom Boom, aka Tabitha Smith, knows all about the use of excessive force from working with the New Mutants and X-Force. having been trained by the likes of Cable and Domino, whether she'd like to admit it or not, she knows the difference between right and wrong. Well, this all comes undone thanks to a moment of immaturity which results in a warehouse blast in Queens, New York that claims several lives.
Early on in th new series' debut issue, we see the original members of X-Force (Cannonball, Domino, Shatterstar and Warpath) unveiling a trove of weapons used to hunt mutants. They're actually investigating why Kid Cable is a potential buyer, and are disturbed because he should be concerned with taking these sellers out, not purchasing munitions from them. As the X-Force team pries deeper, they're led to the European nation of Transia as the supplier, but before they head out, they brutally beat down these arms dealers as a parting gift. What's obvious, though, is that Cannonball (as he's signed up for the Avengers in the past) has made it clear this incarnation of the team has a no-kill policy. The group departs, a bit ticked off that they ran into opposition at all, as Boom Boom was supposed to have scouted the place for them.
In the book's back-up feature, we learn why she didn't do her job. Boom Boom overslept, and as she races to the warehouse late, she encounters the dealers who are barely conscious. Trying to make sure she stays relevant, she conducts an inquiry of her own, not realizing X-Force already got all the info they needed. When one of the criminals fires a gun at her, in a moment of rashness, and angry because she called him an ambulance just seconds before, tosses one of her bombs at him. He dodges it, but it falls near a crate of bombs, triggering a chain of explosions that blows the entire warehouse up.
Boom Boom calls 911 before leaving X-Force a voicemail trying to deflect blame on them for leaving terrorists laying around. But she's clearly missing the important points -- she acted like an amateur, plus we still don't know how much damage has been done to the neighborhoods and citizens around. Also, as she killed dozens of the dealers, X-Force can't even interrogate them again if they have any further questions.
It's a dumb, rookie mistake, one reminiscent of Nitro in Civil War blowing up a huge part of Stamford, thus kickstarting the Superhero Registration Act. This is the kind of behavior that doesn't give mutants a good name, and worse yet, it started with Boom Boom trying to intimidate a thug just to show she had some clout. Someone needs to tell her that with great power -- especially when you can create bombs like she can, using her fingers alone -- comes great responsibility. Boom Boom apparently hasn't let that sink in and one would expect some stern words when X-Force reconnects with her ad learns of her mistake.