With cruel determination and blinding speed, Heart Attack is a Renegade who serves as part of the Monsterous combiner. He is capable of projecting a cycloptic infarction beam from his heart-shaped eye, which also happens to be his weak spot.
While stranded in the multiversal hub of Axiom Nexus, Cy-Kill worked to rebuild his power base with new Renegades. Heart Attack was part of a group of Predacons camped out in the Heap that confronted Cy-Kill during his exploits. After Cy-Kill defeated their leader Fright Face in single combat, the Predacons became loyal members of his Renegade force. Cy-Kill even used his old Puzzler technology to give the Predacons a combiner form as Monsterous. Heart Attack and the others traveled with Cy-Kill back to his home reality when he abandoned Axiom Nexus.
Cy-Kill and his new recruits emerged in the midst of an epic battle between the Guardian fleet and Rogue Star. As Monsterous, Heart Attack and his team gleefully tore through the surprised Courageous before turning on the Command Centers. Unfortunately, Leader-1 tricked Cy-Kill into firing a killing shot at him, which he dodged so that it hit Monsterous instead. This respite allowed the Guardians to retreat, but the Renegades had clearly won the day.
At Cy-Kill's direction, Heart Attack and Clutch used a Space Hawk to recover the remains of the Puzzler construct from the Guardian vaults. Cy-Kill dispatched his creature warriors to Philadelphia as Monsterous to draw Courageous out for another battle, but Monsterous was overwhelmed by a squad of Guardian Boomers. Cy-Kill brought Monsterous to an ambush to try and seize a matter transmutation ring, but the surprise appearance of Courageous made it a fair fight, and so the Renegades retreated again.
When the Guardians and UNECOM came to Quartex to sign a tri-planet alliance treaty with Boulder's Rock Lords, Cy-Kill and Magmar decided to intervene. Monsterous and Puzzler were pitted against Courageous and the Fossil Lords' Fossilsaurus until Cy-Kill tipped his hand and revealed the Renegade Power Suit Warrior, Nemesis. The forces of good rallied, however, and prepared a counter-strike. Monsterous was diverted into battle with the Action Shock Rocks, leaving Courageous and Fossilsaurus evenly pitted against Nemesis and Puzzler in the rematch.
- Heart Attack (GoBots, 1986)
- Giant Monsterous Body
- Heart Attack converts from robot to monster spaceship, and also becomes the lower body of Monsterous.
- Monsterous (1986)
- Renegade Robot Giant
- A straight import of the Devil Satan Six, designed for the anime tie-in toyline Revenge of Cronos, the six components of Monsterous were also available together in a boxed set. They are identical to the individual releases.