(Nightwatch#6) - Cardiaxe avoided notice by Killian Fox by slipping through a secret panel from Dr. Wirtham's office to a soundproofed lab.

(Nightwatch#7) - After reporting to Dr. Morelle (over a secure video channel) that he had finished his assignment, Cardiaxe mused that his newfound power meant that his contract would need to be renegotiated. He then prepared to finish energizing his equipment.

   Meanwhile, Wirtham's long-lost friend Dr. Kevin Trench, who had become the armored crimefighter Nightwatch, was using the building's computers to research nanotechnology in hopes of learning more about his own costume. He was therefore awake and present when Cardiaxe drained all the power in the building. Rushing to Wirtham's office, he was startled by a fully-charged Cardiaxe. Trench was able to escape from Cardiaxe's attack long enough to don his Nightwatch armor, and the two fought briefly until Cardiaxe overpowered Nightwatch. He was preparing to finish the hero off when Wirtham arrived in his guise of Cardiac, having seen the towering Institute building go dark from miles away. As security guards followed close on Cardiac's heels, Cardiaxe attacked them, forcing Nightwatch to intercept the blow meant for them. With the odds reduced to one-on-one, Cardiaxe seemed to have the upper hand on Cardiac, but Nightwatch, though damaged, was able to divert him long enough Cardiac to throw both Cardiaxe and himself out through the window. Nightwatch dove after them, but Cardiac and his hover-hawk glider reached the criminal first, and - after Cardiaxe revealed to Wirtham that he knew his secret identity - Cardiac released him to continue his plunge to the street far below. Nightwatch barely managed to catch Cardiaxe and break their fall with his glider-cloak. Cardiac then returned, intent on killing Cardiaxe, but he was driven off by Nightwatch. Both then departed the scene as the police arrived and took Cardiaxe into custody.

(Dark Reign Files) - Quasimodo researched Cardiaxe for Norman Osborn.

Comments: Created by Terry Kavanagh, Mark Tenney or Roy Burdine, and Don Hudson, Thomas Florimonte, or Richard Perotta.

Nightwatch issues had a lot of artists. I don't know which particular pairing of penciler and inker came up with Cardiaxe, so they're all listed above.