Not long after Mongul's defeat, his son Jochi, and all of Warworld come looking for the warriors who defeated him. Naturally, being the one who flies, Superman goes to confront Jochi, who informs Superman that he is not here to rescue his father, but instead, he would like to meet the the families of the two men who defeated his... Batman and Superman have one day to respond, or Jochi will release Warworld onto Earth.
Soon after Jochi's ultimatum, Bruce finds Clark sitting alone, having listened through the whole conversation through Clark's communicator (which Bruce can turn on any time he wants). They believe Jochi's demand is for some form of tribute, and try to figure out how to respond.
Clark's first choice who to bring with him is Supergirl, despite Wonder Woman volunteering for the job, but Clark tells her that if something goes wrong, he needs the greatest warrior at his disposable down on Earth. Diana doesn't like it, but she sees the reasoning, then gives Supergirl her sword, telling her that there will be a point where she'll need to do what Clark won't.
Elsewhere, in Gotham, Bruce finds Jason beating up on some thugs, using some restraint, and requests that he may need Jason's talents, and lack of shared sensibilities for the coming problem.
Cut to Superman, Supergirl and Steel waiting for Batman and Jason, when Batgirl (also good with listening in on tech) shows up as well, wanting to go too. Bruce isn't okay with this, telling them that this might be their most dangerous threat yet, and things could go very wrong, all while remembering what's happened to both Jason and Barbara, as well as most recently with Damian. Then Jason cuts a bit deep, asking Bruce if he's just now figuring that out, because maybe that's the reason why he's lost so many of them. Clark can hear Bruce's heart pounding, but Bruce doesn't respond to Jason, and they ascend to Warworld with Krypto, who also shows up, and I guess reveals Superboy is dead? I don't know.
The heroes enter Warworld to find that not all is what it seems, as Jochi is in the middle of battle with some of the other council members, struggling to retain leadership. Turns out Jochi is the one member of the council who didn't want to confront Earth. Right now there's a big tournament to figure out who is the new leader, and there's a gun pointed at Earth ready to fire whenever whoever wins says to do it. Jochi begins to lose his fight, which causes Jason and Bruce to step in, which comes with calls of cheating, but Bruce claims since he has defeated Mongul, Jochi is under his authority as a member of his clan. So Jochi wins to fight another day, but is still wounded, which leaves Supergirl to suggest to Clark that they need to enter too, because a wounded Jochi and two humans surely can't win. While all this is happening, Steel and Barbara are sneaking around, trying to figure out how to disarm the gun pointed at Earth.
So Batman, Jochi and Jason continue to fight on one end of the tournament, while Superman, Supergirl and Krypto are on the other. Through their fights, Bruce learns that Jochi isn't very similar to his father Mongul, who believed that change was for the weak, but Jochi points out to look where that got him. Bruce sees some good in Jochi, believing there's hope for him yet.
The end of the tournament draws near, and unfortunately it's the Batman clan vs. the Superman clan, and there are some specific "loser has to die" rules. If either team doesn't adhere to the rules, they'll both forfeit and the Earth will be destroyed... Meanwhile, Barbara and Steel are still trying to disarm the gun. Barbara continues to say they should just blow the controls up, which Steel thinks is a joke... but it's not.
The final fight begins, and both sides know they can't hold back, which is why Bruce brought Kryptonite. Bruce somehow gets Clark on the ground, and is about to deliver a shot straight to the face, but intentionally misses, and hits the ground next to Clark's head. The onlookers in Warworld figure this to mean that neither side will play by the rules, so they attack. Unfortuantely for Warworld, Steel goes with Barbara's plan, and blows up the control, so the guns are a no go. Meanwhile, it's the Batman and Superman clan vs everyone, and as they begin to escape, Bruce tries to get Jochi to come with him, telling him that Warworld isn't his world anymore, but Jochi asks if Earth ever got this ugly, would Bruce abandon Earth? With that, Jochi cuts the line Bruce is holding on to him with, and goes to face the threat head on.
Things go from bad to worse when Warworld begins to fall from the sky, but Superman's got a trick up his sleeve and sucks the whole damn thing into the Phantom Zone.
Sometime later, Clark and Bruce meet, Clark telling Bruce he's sorry for what happened to Jochi. They discuss some allusions to both Damian and Superboy, but it doesn't amount to much, and then Jochi finds his father's blade in his gut inside the Phantom Zone.