The following contains spoilers for Justice League #75, now on sale from DC Comics
The epic death of the Justice League has long been teased as a key moment leading to the Dark Crisis, but in actuality, it's a surprisingly sudden event. Most of the Justice League (and Justice Incarnate) are seemingly obliterated by Pariah, setting up their eventual return. But one hero was actually felled by a physical threat, and the sudden brutal nature of it proves a point about DC's bad guys.
Justice League #75 (by Joshua Williamson, Rafa Sandoval, Jordi Taragona, Matt Herms, and Josh Reed) featured the unleashed Dark Army of DC's greatest villains. While most of them share a common element that makes them weakened by this role, one of them, Doomsday, isn't slowed down in the slightest, reminding readers why he's possibly DC's most dangerous villain.
Justice League #75 featured the long-teased death of the Justice League, with the group facing off with a collection of their most dangerous enemies. Controlled by Pariah and conscripted into his Dark Army, the villains prove to be dangerous, but somewhat hindered. Even the League was able to tell that their foes aren't operating at peak efficiency. While their attacks may have been lethal, they were also blunt and without wit. Even Darkseid seemed to exhibit this, at one point breaking free of the Great Darkness' control and speaking to Black Adam. This allowed the heroes to stay ahead of their foes, sparing most of them until Pariah made his move.
But that isn't the case for Doomsday. The monster is a force of nature in the DC Universe, capable of even fighting Superman to a stand-still and even killing him in his debut storyline. While the likes of Darkseid and Nero might be reduced in their capability because of their restrained minds, Doomsday has no such problems. He's a creature of instinct, with a desire to slaughter everything in his path. Even after reboots to the DC Universe, Doomsday remained as deadly as always. None of that is hindered in his new form, and it makes perfect sense that Doomsday was the only member of the Dark Army to actually strike a hero, seemingly killing Green Arrow with an attack.
It's a good reminder of how simple and effective Doomsday can be as a villain. Thanks to the largely overwhelming power of DC characters like Superman, Wonder Woman, and the rest of the Justice League, many of DC's most dangerous villains are as clever as they are strong. Without their intellect, those who make up the Dark Army would be easily defeated time and time again. The Great Darkness and Pariah don't seem to mind, noting that when everything else is erased from existence it'll be easily able to control their full potential. But Doomsday has no such concerns. There's no real mind to Doomsday or strategy behind his power. He didn't kill Superman through some amazing scheme or long-simmering plan, he just found the Kryptonian hero and beat him to death with his bare hands.
In a sense, this proves why Doomsday is perhaps the most overtly dangerous DC villain. Characters like Lex Luthor and the Joker may have done more damage to their enemies, Nekron and the Upside-Down Man are effectively operating on a level the heroes can't even match. But each of those villains has been overcome and outfought, even when they gain some sort of physical edge. There's no outthinking Doomsday, just staying out of his way and hoping for the best. Of all of DC's most deadly foes, Doomsday is the only one who may have gained an actual kill in the brawl with the Justice League and it's because of his simplicity and straightforward nature. If Superman can barely withstand Doomsday, then someone like Green Arrow is a goner, even with Doomsday just being mindlessly utilized, and that speaks to the dangerous aspect of the character.