Warning: SPOILERS for DCeased: Dead Planet #7.
In the finale issue of DC Comics' John Constantine did the most surprising thing he's ever done: he actually saved the world as a legitimate hero, sacrificing himself while battling the demon lord Trigon in one of the most epic magical battles of all time. While many heroes weren't sure what Constantine was planning in the issues before the series' conclusion, it ends up being exactly what was needed, giving the rest of the surviving heroes time to cure the world of its anti-living hordes.
While many of the heroes still standing in Dead Planet were focused on creating a cure for the anti-living zombie virus that had plagued the world, Constantine was focused on another threat entirely. Because the anti-living were neither alive nor dead, the demon lord Trigon wasn't getting any new souls for his domain. As a result, Constantine learned that Trigon was planning to raze the entire planet in a cleansing fire. If Trigon were to succeed, there'd be no one left to ister the cure (and no one left to receive it). As such, Constantine rallied a team of survivors in order to embark on a wild quest retrieving a variety of extremely powerful magic items, some of which required methods that were pretty questionable to obtain.
While there were deep losses and heavy criticisms, Constantine eventually had everything he needed, just in time for Trigon's arrival in Dead Planet #7 from writer Tom Taylor and artist Trevor Hairsine. Wearing the Cloak of Ragman powered by corrupted souls as well as the Helmet of Nabu, Constantine went to work fighting Trigon to the death, using the multiple weapons and powers he had procured to great effect.
However, even with all these great magical relics at his disposal, Trigon still emerged victorious and killed Constantine near the issue's end, much to the anguish of Zatana. However, dying was all part of the plan. Constantine had prepared for his own death, which is why he had also taken the power of Boston Brand, also known as Dean. Still connected to all of the new powers he had gained, Constantine flew into the body of Trigon, and took possession of the demon lord. He then forced Trigon to stab and kill himself with the Spear of Destiny.
With Trigon dead, Constantine faded away and died a hero's death, having won one of the greatest magical battles of all time in the DC Multiverse. Furthermore, without the threat of Trigon looming, the rest of the heroes were able to get the cure across the globe, finally ending the anti-life zombie virus once and for all. And it was all thanks to John Constantine of all people. Before the final battle, Superman told John that he was a good man. While Constantine disagreed at the time, he certainly proved his Superman right and his ability to be a great hero with his epic sacrifice by the end of DCeased: Dead Planet from DC Comics.