The Doomsday Clones is a series of genetically engineered clones created from the savage intergalactic serial killer Doomsday which had superhuman strength, invulnerability and the ability to create shock-waves either through his strength or energy-manipulation: they serve as villains in the DC comics.
One of the Doomsday Clones boss in the video-game, Justice League Heroes - he is based physically on the Doomsday found in the Animated DC universe but is more intelligent than most incarnations of the beast, being capable of speech and higher-functioning plans. Although downgraded, the Doomsday Clone was too powerful for the heroes to defeat by traditional means, so they had to use a powerful laser-weapon to weaken the monster sufficiently for them to defeat him.
The Doomsday Clone infiltrated the Justice League Headquarters with the aid of Brainiac and attacked a lone Martian Manhunter while the others were occupied with a White Martian invasion and a Gorilla Grodd assault (all orchestrated by Brainiac). After the heroes fought through their own security-system they were confronted with the Doomsday Clone, who also had the aid of Minor Clones, which were smaller versions of himself.