I don't own Justice League or Harry Potter and S.T.R.I. P. E.'s armor is the big one from seasons one and two.
Batman, Flash, and Orion went to the grand opening of the new Flash museum and were attacked by Captain Boomerang, Captain Cold, and Mirror Master but the trio of heroes beat the trio of villains.
Deadman asks the Master of a Temple for advice, as he has not passed on despite catching the man who killed him. The Master says the destiny of Deadman is to avenge his death. On Grodd's orders, a team from the Legion of Doom attacks the temple of Nanda Parbat, to steal its Heart, containing the psychic remains of thousands of former monks. Deadman tries to stop them, but is helpless to prevent Black Manta from killing the Master and is exorcised by Tala from Rampage. Tala takes the Heart of Nanda Parbat and transports the villains away.
Deadman goes to the Watchtower and possesses Superman's body to tell them about the disaster. Batman vouches for Deadman, having met him before while helping to solve his murder; Batman is also one of the Master's former pupils.
While puzzling over what Grodd is planning to do, Deadman/Superman says he can feel the psychic presence of the Heart, but can't narrow it down further than Africa. Realizing that Grodd has returned to Gorilla City, Batman radios Solovar, who tells them that he was just going to call them and that the city is under attack at that moment.
Batman, Wonder Woman and the possessed Superman arrive outside the city. Deadman leaves Superman's body to slip through the protective shield and find someone to possess in order to shut it down. The Leaguers fight their way into the city. Deadman possesses Wonder Woman in order to attack Black Manta but decides not to kill him.
Inside, Grodd and Luthor places the Heart, which Grodd describes as an exotic power source, into the force field generator, creating a device powerful enough to send out a planet-wide energy field. Luthor assumes that Grodd plans to extend a mind-control signal over the Earth, but instead Grodd reveals that his master plan is to "re-write" human DNA and transform every person on Earth into apes.
The signal reaches out and transforms the Justice Leaguers, but Superman manages to destroy the generator and the Heart, turning themselves back into humans.
Black Manta sneaks in and aims his weapon at Wonder Woman. Deadman takes over Batman's body pullls out his grapple gun and slams Black Manta onto the floor knocking him out.
At the Legion of Doom's headquarters, Grodd insists that "their" master plan has suffered a temporary setback, no more; then Luthor stands and aims a gun at him, announcing that he's decided to take over leadership of the Legion a little earlier than he planned, since he's disgusted that Grodd's "master plan" (a) didn't work, and (b) was just plain ridiculous. Luthor incapacitates Grodd during a council meeting by shooting him with a non-lethal weapon and declares himself the new leader. The Legion are equally disgusted with Grodd, so no one objects. Tala, especially, is quick to transfer her affectionate attention to Luthor.
A flashback depicts a World War II mission of the famous All Star Squadron member Spy Smasher, who invades a secret Axis laboratory and steals a syringe containing an experimental super-soldier serum, a fight resulting in the Laboratory being set on fire, and an explosion wrecking the Castle. Moving into the present, we see that General Eiling, former military liaison for Cadmus, is reviewing the sixty-year-old casefile.
Eiling dines with former colleague Amanda Waller, who has greatly softened her anti-Justice League-stance since the Lex Luthor/Brainiac affair. Waller says they were lucky to avoid jail. She advises Eiling that the times are changing, and strongly suggests that the old soldier should change with them, comparing the League to the Soviets.
Meanwhile, aboard the Watchtower, Mr. Terrific has a mission for some of the Justice League reservists. STRIPE, Stargirl, Vigilante, Shining Knight, Green Arrow, Crimson Avenger, and Red Arrow are dispatched to Metropolis to cover what is normally a job for Superman. However the League is spread very thin. The septet assumes public relations duty aboard a parade float paying tribute to Metropolis' heroes — the police and fire departments, much to Stargirl's chagrin. The spectators are at first disappointed by Superman's absence, but soon begin to warm to his non-powered teammates thanks to Vigilante's knack for showmanship.
Eiling is unconvinced, feeling that metahumans can't be trusted and that the Justice League didn't disarm their fusion cannon, and decides to take action. He sneaks into Cadmus, knocks out a guard and forces a scientist to get into the lab. He steals the old Captain Nazi serum. After injecting it into his body despite the scientists advice, Eiling transforms into a monstrous brute of a man with fangs and grey skin. Vowing revenge against Superman, Eiling springs into the air with incredible superhuman strength and heads for the one place he figures he can find the Man of Steel.
Eiling disrupts the parade with a thunderous impact and sends the crowd into a panic. At first, S.T.R.I.P.E. is able to engage him, but even the Justice Leaguer's powerful armor is no match for Eiling's Doomsday-level strength. Stargirl attacks with little effect, and it is all Vigilante can do to keep the bystanders safe with the help of some local children. Eiling bellows out for Superman to face him, but instead he is faced by Green Arrow, Vigilante, Shining Knight, Red Arrow, and Crimson Avenger who fare poorly against the powerhouse. Then Mr, Terrific beamed Thunderstorm and Mass Extinction who were back from their mission. Thunderstorm drenched him with rain then zapped him with bolts of lighting while Mass Extinction was clubbing him as an Ankylosaurus of course they didn't do it at the same time the Mass Extinction shape-shifted again this time as a Supersaurus and kept using the weight of the sauropod against him eventually they brought him down while Mass Extinction simply commented with good riddance.