The Avengers #289

In "The Cube Root," the Avengers face a high-stakes assault on Hydrobase as the Super-Adaptoid, leading Heavy Metal—Machine Man, Sentry 459, and Tess-One—unleashes a calculated strike. With the Adaptoid’s true motives finally exposed, Machine Man turns against his former ally, helping the team fend off the attack while the Cosmic Cube arrives in the form of the sentient being Kubik. Written by Ralph Macchio and illustrated by John Buscema, with inks by Tom Palmer and colors by Paul Becton, the issue’s cover by Buscema and Palmer captures the tension of the moment.