Atum resides in the sun and is completely immune to the heat, pressure and cosmic forces of the sun. He can fly at light-speed, generate intense light and heat. He can also absorb/consume foes thereby gaining all of their abilities. Atum is by a considerable margin one of the most powerful entities of the whole Marvel Universe
The reason why atum was made in the first place. Set and the other Elder Gods started killing each other off for each others power. So Gaea wanted to end all this violence. Gaea called upon the Demiurge, the physical manifestation of the potential life-force of Earth and source of Gaea herself, in order that it might engender within Gaea a new kind of being. Atum arose from within Gaea fully formed and in full possession of his powers. Wielding the powers of the sun itself, Atum attacked and began to slay the elder gods, who at this time degenerated themselves into demons. As he killed them, he absorbed their essences, becoming the Demogorge. Eventually, Demogorge slew and absorbed all the demons, save for Chthon and Set, who escaped into other dimensions and tricked Demogorge into destroying lifeless replicas of themselves. Content that he had accomplished his mission, Demogorge reverted to Atum and flew upward where he merged with the sun itself.
The first only fear being eternity was a good showing, it represents the classic aspect of demogorge who was that powerful it would feel eternity was the only fear lol.
Every thing els ein godsquad was utter crap for him. Getting hurt by a no name god? Hercules being able to jump kick him? Dieing to a shapeshifting skrull god because it had to many gods inside of it? When we clearly remember him eating billions of those in the beginning of time and leaving only two? For Godsquad they f him over big time making him so weak even a regular Demogorge who pawn the likes of Thor with ease and not even notice his hammer hitting him and beat set, so that little shapshifting god should have been a joke not even close to a threat. What made it even more fake was he use to be like 20ft and everytime he ate a god it had a mark of its fake on his body you could see, this time he just swallowed her and then nothing came out which showed the writer had no idea about the character.