Megadeath is, even by Decepticon standards, quite mad. Rather than fighting for territory, Megadeath wants to sterilize whole regions of Cybertron with neutron bombs, then moves in to occupy them. This callous disregard for life horrifies even Decepticon High Command, who forbade the action and scuttled his chances of moving up in the ranks.
Megadeath has quietly recruited an elite cadre of troopers, including Thunderwing. He has cultivated and shaped these young Decepticons in his own image, to be loyal only to him on the day he may publicly challenge Megatron.
A master of psychological torture, Megadeath denies his victims respite or escape until they invariably bend to his will. He instills feelings of need, fear, helplessness and despair, then makes his victims reinforce those feelings via their own choices.
Megadeath's three closely-set eyes can fight powerful laser beams, and he has concussion cannons on each forearm. His is also equipped with missile launchers. He transforms into a bombing aircraft equipped for high-altitude observation. To power his exorbitantly energy-consumptive primary weapons, there is a nuclear power core burning behind plexiplastic inside his chest.
Long association has led Thunderwing to label Megadeath's mastery of psychological torture an 'unhealthy obsession.' Megadeath's need to prove he has bigger ball-bearings than the next 'bot will eventually get them chopped off.
Marvel Comics UK continuity
Megadeath planned to go forward with his nuke-and-colonize plan even after High Command's veto, planting six neutron bombs throughout the Stanix region and making arrangements to temporarily evacuate his troops for the detonation.
(It's worth noting that neutron bombs, as defined by Earth science, are more lethal to organic life, and less damaging to technology, than "conventional" nuclear weapons. They also produce less "bang" for the same production cost. Why Megadeath chose to use them against purely technological targets is thus unclear.)
The arrival of a group of Autobots known as the Magnificent Six threatened to expose Megadeath's scheme. He ordered his elite cadre, led by Thunderwing to bombard Yuss, the town where they were hiding, eventually forcing the residents to turn the Autobots over.
Megadeath supervised the torture of the six, breaking them so that when he finally killed one of their number, the others could not lift a hand to stop him. He then forced the Autobots to search for the town's residents (whom he has concealed nearby) before the neutron bombs exploded.
Circling above Yuss, Megadeath did not see the Autobots searching frantically as time tic'd down. Instead- they seemed to have disappeared! Landing to investigate, he was immediately attacked by the Autobots, who had hidden themselves in order to draw him out. The Autobots crippled his right leg, rendering him unable to transform and trapping him at the epicenter, but Megadeath still refused to tell them the townspeople's location. Eventually, the Autobots were forced to leave him, and them, behind as the neutronic bombs exploded. The Decepticons viewed this whole affair and Megadeath himself as an embarrassment even four million years later.
Megadeath, unexpectedly survived the neutron bombs, and the ensuing environmental catastrophe that turned Stanix into the Acid Wastes. The Yuss residents also survived, though horribly mutated by the explosion. They lived under his rule deep in the Acid Wastes for four million years...
In 1991, Optimus Prime sent the five survivors (and Silverbolt) back to Stanix on an unrelated mission. Megadeath captured them, intending to torture them once again. Instead, they overcame their collective guilt and heroically rose up to beat Megadeath to death with their bare hands.
Megadeath breached the plexiplastic plate protecting his reactor rather than be taken into custody and put on trial for crimes against the Transformer race.