An earthquake shatters the lands far North, and a trawler crew spot a revealed Viking ship in its wake. Green Arrow greets Wonder Woman in her civvies, who is attending a "save the Earth" conference. She asks J'onn along, who is reluctant to come. Wonder Woman determines he's unsure of interacting with humanity, and suggests he interact with humans.
The Legion of Doom are meeting and having Lex report how he's augmented various Legion members' powers. Grodd tells of the story of Prince Jon, a Viking Prince, who was enamored with a Valkyrie. When Odin found out, he banished Jon but promised that if Jon suffered a heroic death, he'd be reunited with his love. But Odin granted Jon invulnerability and the despondent Viking wandered the Earth, sailing beyond the knowledge of mankind. But now Grodd has word of the discovered Viking ship and wants the corpse stolen so that Lex can determine the secret of his invulnerability for his mysterious "ultimate goal."
Diana is at the conference which is near the Viking ship, and not having much luck. She goes outside and spots their liaison, King Faraday, who is part of the American security team. She's interrupted by an explosion and goes to investigate – the Legion of Doom are attacking the guards and easily overwhelming them. Wonder Woman arrives but is hit with a poison dart.
The Legion prepare to dispose of her but are interrupted by Faraday and his agents, using flying harnesses and ray guns. They are soon overwhelmed and Wonder Woman calls J'onn for support. J'onn sends Green Arrow and Mr. Terrific, and Wonder Woman insists a reluctant J'onn replace Terrific. J'onn scans Giganta's mind to learn what they're after before her mind shuts down. The Legion summons a sub to pull the Viking ship out of the ice and into the waters, bringing an avalanche down on the conference.
Green Arrow boards the sub and takes out the troopers as the submarine goes down – he gets inside barely in time, while Wonder Woman swims after them in pursuit. She tries to free the Viking ship while Legion member Devil Ray attacks and J'onn captures Killer Frost as she goes after the conference. Wonder Woman takes out Devil Ray, shattering his helmet and leaving him to drift to the surface, while J'onn forces Killer Frost to stop the avalanche or die along with the conference attendees. Frost manages to stop it while Wonder Woman goes back to the Viking ship and Green Arrow takes out the troopers inside and releases the ship before being captured. However, Faraday arrives with three subs and forces the sub crew to surrender.
They return Jon's ship and Wonder Woman offers to lay him to rest according to tradition and she'll take care of it. J'onn announces that he's taking a leave of absence to find a way to contact with humanity. In deep space, Wonder Woman uses a Javelin to launch Jon's ship off into the sun while reading an elegy to him, while the other Leaguers bid J'onn farewell. The Martian Manhunter assumes human form and goes among mankind.
The Viking Prince
The Viking Prince first appeared in Brave & The Bold #1 (Sept. 1955). His origin seems to vary but essentially he is Jon, son of the Scandinavian King Rikk (either natural born or adopted), fought for his people and defeated many mystic creatures enemy tribes, and foreign invaders. From time to time he was drawn through time and met the Justice League and other 20th century heroes, but always returned to his own time until when he ended up in World War II and was killed in an explosion. The Viking Prince is a normal human but with superior strength and endurance, and a high degree of skill with the axe, the sword, and the fist. This is his first appearance in the WB animated universe.
Heatwave first appeared in Flash Vol. 1 #140 (Nov. 1963). Mick Rory was fascinated by flames and also gained a fear of cold when he was locked in a meat locker. Inspired by footage of the Silver Age Flash and his Rogues Gallery to don an asbestos suit, developed a flame-pistol, and turn to a life of crime. He fought repeatedly with the Flash in Central City and became a member of the Flash's Rogues Gallery himself. Later he reformed and worked as a consultant to fire stations and arson investigators, but his ongoing pyromania has drawn him back to crime occasionally and he has recently (as of the time this episode aired) returned to full time villainy. This is Heatwave's first appearance in the WB animated universe, although an actor dressed as him appeared in "Eclipsed (1)".
There is no "Devil Ray" in the DC universe. However, he bears a startling resemblence to an Aquaman villain, Black Manta. In case you're interested, Black Manta first appeared in Aquaman Vol. 1 #35 (Sept.-Oct 1967). Initially very little was revealed of his background – he was apparently a normal human who used specialized aquatic gear to plunder the Seven Seas. He used a special diving helmet with a laser built into the helmet eyes, and a manta-ray sub. It was later revealed he was an African-American who claimed he was fighting for freedom for "his people" in the water after centuries of oppression on the land. He killed Aquaman's son, escalating their rivalry, and later Black Manta made a deal with the demon Neron to gain greater power. He was transformed into a human/manta hybrid but was later cured by Aquaman after it was revealed he was autistic as a child had supposedly turned him into a villain. The two were brief allied but he turned against Aquaman. Black Manta currently possesses no superhuman building but is an expert in underwater technology and is a competent swimmer and fighter. This is "Devil Ray's" first appearance in the WB animated universe, although in the Challenge of the Superfriends
TV series Black Manta, who looks almost identical to him, was a member of the Legion of Doom.
Mr. Terrific first appeared in Specter #54 (June 1997). Michael Holt was a protege and self-made millionaire who despaired after the death of his wife in a car accident. He wandered into a gang fight and was prepared to let them kill him without a fight, but the Spectre appeared and reminded him of the Golden Age Mr. Terrific, Terry Sloane. Holt resolved to fight on behalf of "fair play," help the underprivileged youths, and fight crime. Taking the name of his predecessor, the new Mr. Terrific joined the Justice Society and quickly rose through the ranks to become the Chairman.
While Mr. Terrific has no superhuman abilities, he possesses a photographic memory, has gathered five black belts in various martial arts, and has mastered hundreds of skills and sciences. His primary expertise is in cybernetics, and he employs a series of flying T-Spheres with limited artificial intelligence, capable of projecting holographic images and cloaking Terrific from any electronic detection, and acting as blunt projectiles and electrical burst-type weapons. This is Mr. Terrific's first significant appearance in the WB animated universe.