CONDUIT!

Conduit's threat against the Man of Steel began with an assassination attempt on Clark Kent. Conduit took Superman's timely arrival on the scene as evidence of Kent's incredible luck, and challenged Superman to a battle. Despite being able to radiate kryptonite energy, Conduit proved no match for Superman. He was captured and taken to STAR Labs for study.

While at STAR, Conduit discovered the explanation for Kent's incredible luck, and the fact that Superman always seemed able to bail the reporter out of any crisis: the two were one and the same!

Conduit took this information very personally, and it wasn't too difficult to see why: Conduit was, in reality, Kenny Braverman, who had grown up with Clark Kent in Smallville. Kenny and Clark had always competed against each other, and Kenny had always come in second to Clark. At the time, Kenny had put it down to Kent wanting to win more; but this new discovery provided a completely different explanation. Clark had always beaten Kenny because Clark was really Superman!

Armed with this information, Conduit escaped STAR and began a campaign to destroy Clark Kent and his friends and family. He attacked Pete Ross and Lana Lang, and sent agents after Jonathan and Martha Kent as well!

These repeated attacks on those nearest and dearest to him led Clark to briefly abandon his life as Clark Kent, and as Superman. But when he realized how impossible that would be, Superman faced Conduit in one last battle, held at an arena Conduit had designed to look like Smallville High Stadium.

The battle was fierce, with both fighters giving it all they had. But in the end, the kryptonite radiation Conduit's body was capable of creating wound up killing him.