So, have you heard of The Death of Superman? If you have, then you may get the supposed importance of Superman Doomed, a massive Superman story event which took place.
Doomsday is the 90s villain that ‘killed’ Superman. Imagine The Hulk covered in rocks and buried in plot armour. Of course, Superman wasn’t really dead and Doomsday wasn’t either. Despite the double K.O. they took part in.
Back to the present, Doomsday is back and is causing havoc on Earth. Superman realises he may actually have to kill Doomsday, because it seems to be the only way to stop him. So, the man of steel confronts Doomsday and rips him apart. When Doomsday splits open he releases a ton of spores, Superman uses his super breath to suck it in. That’s where it begins.
With Superman sucking the spores, he’s got the Doomsday infection. This will gradually turn him into Doomsday. The infection begins to change his physically, but more noticeably, it changes him mentally.
Superman and Clark Kent become more violent and aggressive, leaving super villains and evil doers in smoking craters. In a sense, the Doomsday infection is a metaphor for the recent film incarnation of Superman, and why Superman shouldn’t be this way – a brooding and angry individual who lets his fists do the talking.
So the US Government attempt to stop Superman with Kryptonite bombs when Superman’s infection worsens and he begins to look more like Doomsday, but ends up dispersing Kryptonite gas over the planet.
As Superman leaves the planet to avoid any more dangers, the Red Lantern Supergirl (Supergirl with a Power Ring powered with rage) drags him away.
Deep in space, Superman find a fleet of Brainiac war ships heading for Earth. Their goal is to suck the heads of every human dry. Back on Earth, people find out Lois Lane has fallen under the control of Brainiac, the evil genius collector of worlds.
Superman returns to Earth and eventually confronts Brainiac and finds out his whole quest is to absorb knowledge to bring his dead family back. Superman breaks the control he has over Lois and throws Brainiac and his fleet into a black hole.
Which cleans away the Doomsday infection. Nicely convenient. Overall the arc is good, a little long and tedious, but the splash page where Superman uses the sun to fire a huge heat blast, is pretty ace.