Karl Coven was a convicted serial killer, taking the lives of seventeen people including women and children. He claimed throughout his trial he was an alien from a far-off world and not subject to human laws; however, various medical procedures established he was a normal human, and his claims were deemed an attempt at an insanity plea. It was not accepted by the jury, and testimony from Rick Jones who witnessed one of Coven’s heinous acts sealed his fate, and Coven was sentenced to death by lethal injection. Moments after he was pronounced dead by two medical doctors, Coven miraculously revived himself, again attributing this to his alien physiology, and asked to be released from prison. The presiding judge declared Coven served his sentence and to detain him further would violate his eighth amendment rights. Soon after his release, Coven tried to enact his revenge on Rick for helping send him to prison, but he only grazed Rick's head with a bullet fired from a rifle on a rooftop across from Rick's apartment. Coven decided to finish the job up close and personal, but Rick switched places with Captain Marvel (Genis-Vell) who he was molecularly bonded with at the time by hitting the Nega-Bands on his wrists together. Coven chose to hear what Marvel had to say, especially since Coven could not kill him and further violence would have only resulted in Coven’s immediate death.
Captain Marvel had become intrigued with Earth's legal system and wanted to perform an experiment with Coven's help. After witnessing Spider-Man (Peter Parker) save a seemingly distressed extraterrestrial named Tlaango from the much larger Caffrey of the Borozil Clan, Marvel chose the two visiting aliens as plaintiff and defendant while kidnapping and forcing Spider-Man to act as defense attorney while Coven acted as prosecutor. Although Spider-Man played along, he could not end the mock trial before determining Caffrey was not trying to hurt Tlaango, or prevent Coven from snapping Caffrey's neck for talking out of turn. Rick then discovered through his mental link with Marvel that Marvel shared some of his cosmic power with Coven.
Coven no longer wanted to kill Rick because he did not want to risk severing his connection with Marvel and lose his powers. Lucy Harper, the widow of a police officer murdered by Coven, visited Rick unannounced, hoping she could convince him to call on one of his friends in the super-hero community to catch and kill Coven. Coven then abducted her from Rick's apartment. When Marvel refused to save her, Rick saved Lucy by causing a building to fall on Coven, but he knew this was only a temporary delay. Rick hid with Lucy in Ridley's No Freakin' Way Museum, but Coven found them and threatened to kill them until Marvel took back his power at Rick's demand. Coven surprised Marvel by stealing back the power he had and then some because his alleged alien physiology allowed him to do so through their psychic link. Immediately after Coven's apparent triumph, Tlaango returned with Ulzak of the Borozil Clan to mete out justice for Caffrey's unwarranted execution. Coven was given the choice to go peacefully, but he chose not to, believing his power made him unstoppable. Right before the aliens opened fire on Coven, his powers were stripped away by Marvel, leaving Coven to die a death he could not cheat.