Umbra was once the ruler of a heavily fortified planet known as Warworld. His brother, Jaagur, commanded a rival army that presented an obstacle to Umbra's quest to rule the galaxy. When chief scientist, Myrrhot, designed a Star-Tap Siphon to extract energy from a distant star and funnel it to his battle armor, Umbra became confident that Jaagur could be defeated. In response, Umbra instigated a war with Jaagur by sending an unencrypted signal that revealed the location of his forces to lure Jaagur to Warworld. General Damos advised Umbra that the army of Warworld would face heavy casualties, yet Umbra, motivated by desire for conquest or mere hatred for his brother, dismissed the General's concerns and pressed ahead. Meanwhile, Jaagur discovered the signal and arrived at Warworld. After easily dismissing the defenses of the fortress, Jaagur met Umbra and they begin to battle each other. Meanwhile, the Star-Tap Siphon was draining the Earth's Sun's energy, which attracted the attention of the United States' government. They enlisted the aid of Mister Fantastic of the Fantastic Four to resolve the problem. Reed built a device to stop the siphon, which he deployed successfully. However, destroying the Star-Tap siphon created a portal galaxies away on Warworld that pulled in Umbra and Jaagur, as they did battle, to Earth's solar system, merging their bodies into one powerful being.^[1]

After being merged with Jaagur, Umbra dominated their dual form and attacked Earth. The Fantastic Four managed to defeat him through the brute force of the Thing, who, distraught over recent events, mercilessly beat Umbra into submission. Umbra and Jaagur were detained, and Reed successfully split Jaagur and Umbra. After the split, Umbra attacked Jaagur and slammed a power coupling into Jaagur's armor, creating an explosion. After the explosion, neither Jaagur nor Umbra were found. Reed hypothesized that they were destroyed.^[2]

• Battle Armor: Suit capable of absorbing energy and discharging it. Reed Richards noted that the circuitry is advanced far beyond human technology.^[2] His armor is able to project a force field that enables him to travel through the vacuum of space.
• Star-Tap Siphon: Device capable of draining the energy of a star galaxies away and providing it to Umbra's battle armor.

• The Marvel Encyclopedia #Fantastic Four calls Umbra's home planet "Darbia," but this term is not found in his comic book appearances.