You have just uttered your own epitaph, green-skinned one! Tyrannus ordered me to bring you to him… alive, and of your own free will! But if you will not come of your own free will… and alive… then I am sure he would prefer to have you… dead!!
Mogol was a robot controlled by Tyrannus. As Mogol had no memory, Tyrannus easily convinced him that Tyrannus had saved Mogol from certain death and thus Mogol was indebted to Tyrannus. Tyrannus' rival the Mole Man and his forces knew this truth.
Tyrannus sent Mogol to the surface world to recruit the Hulk in his war against the Mole Man. The Hulk, distrusting Tyrannus after a previous encounter initially fought the Mogol as he would oppose to any agent of Tyrannus. However, Mogol insisted in being friendly (because he recognized the Hulk as a peer, unlike the weak Tyrannoids in his environment), and the Hulk agreed to follow Mogol to Subterranea, where both worked together for Tyrannus.
When the Hulk discovered that Mogol was a robot, the Hulk destroyed him, believing that Mogol was a trick to make Hulk fight for another people's interests. Mogol refused to defend himself against the Hulk, claiming that they could still be friends, but the Hulk annihilated Mogol. Then, the confused Hulk rampaged both Mole Man's fortress and Tyrannus' city in the memory of his friend.