"Umbu, the Unliving!"
Ka-Zar realizes that he needs the help of not the Hulk, but Bruce Banner if the deadly machine is to be stopped before it triggers world calamity. The Hulk lashes out at Ka-Zar and Zabu, leaving Ka-Zar to be captured by the Swamp Men. We see how the Swamp Men worship a gigantic living idol, Umbu the Unliving. The idol is in reality a sophisticated android left by an alien race to protect their mysterious machine. Umbu sees the Hulk as a threat and the two face off. Umbu uses gas against the Hulk, triggering his transformation back to Banner, who realizes what must be done. Banner makes his way back to the machine and de-activates it, but exposure to the machine's radiation takes it's toll, and when Ka-Zar arrives on the scene, he finds the apparently dead form of Bruce Banner. 20 pages.
Reprinted in Marvel Super-Heroes (1967) #64.