Warning: SPOILERS for AXE: Judgment Day #5Marvel Comics finally shows how its most powerful characters, the godlike Celestials, actually fight. Just like the other Marvel cosmic beings, the Celestials are usually too powerful to engage in real fights. However, the resurgence of the Progenitor during Judgment Day and the consequent attack of the assembled forces of Earth's heroes against the Celestial was a chance to show how these almighty creatures do battle.
The Celestials are unfathomable space gods who experiment on the primitive creatures of planets such as Earth, creating two different races: the perfect, immortal Eternals and the hideous Deviants. They are also cosmic judges who come back to their "experiments" to see if they are worthy of survival or otherwise have to be destroyed. Earth escaped this catastrophic judgment several times in the past, until the recent resurrection of the Progenitor, the first Celestial who visited Earth in primordial times and whose corpse was used by the Avengers as their base. After the Progenitor was resurrected to stop the disastrous war between X-Men and Eternals, the space god decided it was time to judge Earth, with the outcome being total annihilation.
In AXE: Judgment Day #5, by Kieron Gillen, Valerio Schiti, and Marte Gracia, the heroes attempt one last gambit against the Progenitor, before the creature can destroy the planet. They mount a huge assault, with the purpose of distracting the Celestial long enough to allow a team of the most powerful heroes to strike at his only (supposed) weak spot, opening the way for Thor to land the decisive blow. Faced with this, the Progenitor is forced to do something that his race never does against inferior beings: fight. Because "to be a god is to be creative", the Celestial starts killing heroes in the most creative ways, making Cyclops vulnerable to his own optic blasts, giving instant cancer to Captain Marvel, or making Thor's entire body "unworthy". After this onslaught, what little is left of the forces of Earth retires from the battlefield.
Usually, creatures of cosmic significance such as the Celestials, Galactus, Eternity, or the Living Tribunal do not "fight" in the sense that normal heroes do. Their battles involve massive discharges of cosmic energy or, on more significant occasions, take place in the realm of concepts and ideas as much as in the physical one. The epic and tragic battle against the Celestial Progenitor was the first time that one of these creatures actually had to display its prowess in a fight, and it was as impressive as expected. The authors decided to show how "creative" a god can be when he decides to deal with inferior creatures, and the result was some of Marvel's most shocking kills, such as Thor's gruesome death.
The battle against the Progenitor was a great chance for Marvel to give a new perspective to some of its oldest and most mysterious characters. In the past, some powerful heroes and villains were able to defeat a Celestial, including Thor himself and Thanos (who actually wiped out every Marvel cosmic being more than once). This time, however, the battle was much more physical in nature, and it managed to show how cruelly creative Marvel Comics' most powerful characters, the Celestials, can be when they decide to actually fight.