While defending against an onslaught from him, Saitama stated that Garou had improved a little, which angered the hero hunter, who with a punch knocked him into a currently exploding volcano. Garou immediately charged at Saitama and struck him with both of his open palms, causing the mountain behind to shatter due to the powerful impact.
After the attack, Garou was on his knees and panting, while an unharmed Saitama simply punched him away. Recovering his balance, Garou was impressed that Saitama could withstand the attack that had destroyed the volcano behind him. Also, hilariously following in the current course of things, Garou had accidentally saved an entire city from being destroyed by the volcano's lava. And again, Saitama noticed this random act of so-called kindness and almost taunted him, commenting that Garou had a great hero's instinct, which reminded him a lot of King.
Garou grew two more arms and continued his onslaught. However, he was now visibly showing signs of panic as he fought back against the bald man. Despite being attacked by the hero hunter, who was using all four of his arms, Saitama effortlessly managed to dodge and parry a flurry of Garou's punches with only one hand, while also telling him to just straight up stop fighting.
Afterwards, Garou placed two of his hands on Saitama and took a form that resembled a jet, while his remaining two arms emitted energy to act as propulsion. He then followed up with a mighty attack called Extreme Fujin. Garou pushed Saitama into the ground, creating an intense seismic wave that passed directly through the Earth's core. The attack was so immensely powerful that it distorted the spacetime around the Earth, moved oceanic plates, and even made an entire continent rise up from the other side of the planet. It even messed with the magnetic and gravitational fields of the planet, putting it as a whole at risk.
Despite all of his efforts, Saitama was still unfazed by Garou's earthing attack, and retaliated with his infamous Consecutive Normal Punches. As the two of them returned from the Earth's depths, Garou tried to fend off Saitama's flurry of punches, but failed.
At this moment, he recalled the abominable fist that Sage Centipede had once mentioned, and deduced that it had been referring to Saitama instead of himself. The bald king proceeded to punch Garou directly in the face, snapping him back to reality while causing him to crash through several mountains and eventually fall into a massive puddle.
As he slowly got back up, Garou was shocked and angered by Saitama's overwhelming power, viewing him as the embodiment of unfairness. Because of this, Garou charged at Saitama with a punch, refusing to lose to him. However, Saitama punched Garou before he could land his own, and sent him flying away, destroying Garou's monster form and exposing his true human body that had been buried inside his monster's exoskeleton.
As Garou lamented being beaten by such unfairness, he heard a voice calling out to him. The voice told him that there was only one fist that could counter the fist that is turned against God. He then saw an apparition of Bang hovering above him and offering him his hand. At the same time, massive storm clouds appeared, revealing something like a pair of legs, gigantic, belonging to no body anyone could see.
With everyone witnessing this, Saitama ominously noted that something was coming. In that moment, he saw Garou leap down from behind to face him once again. Saitama exclaimed that Garou had changed costumes again, while Garou, having received the power from the one they call God, replied that the only way to counter the fist that has turned against God is the fist of God itself.
Now appearing as a void of stars and galaxies in his new awakened Cosmic Fear Mode, he took a fighting stance and prepared for another round against the one and only invincible hero. Having now gained the knowledge of all of the flow of energy that courses through the universe, as well as the behaviour of the forces of the cosmos, Garou utilized said flow of energy to send a cataclysmic attack towards Saitama, called Life Eradication Fist, Mark: Nuclear Fission.
The attack resulted in a massive nuclear explosion, which was instantly followed by several more that reached up into the sky as Garou continued to attack, while the surviving heroes — including Psykos, who had emerged since her defeat at the hands of Tatsumaki — stared in amazement and horror at the nuclear blasts exploding nearby.
Despite the enormous force behind the attacks, Saitama was much more concerned over his outfit, which left Garou utterly bewildered. Nevertheless, Garou proclaimed that he felt like he could do anything, before explaining to Saitama that in martial arts there are secret techniques known as shakai, wherein martial artists can borrow the power of nature by imitating the movement of living things.
Garou preferred to address them as modes, since to him they sounded cooler that way. He then demonstrated one of these modes — that being Mode Saitama. As Saitama's own face appeared in place of Garou's featureless, void-like face, Garou duplicated and utilized Saitama's Consecutive Normal Punches, assaulting the hero with his own technique, prompting Saitama to respond with his own Consecutive Normal Punches.
Their fists collided in an exchange of blows, creating an enormous destructive force that pushed out around them, destroying everything in its path. The exchange of blows ended with Saitama and Garou simultaneously landing a blow to one another's faces, sending them both directly into the water below.
Instantly, they both leapt back out of the water, with Garou then taunting Saitama on how he must be at a loss for words upon finding someone who could finally match his strength. Saitama, though, was slightly dismayed, as he thought back to how he had promised Tareo he wouldn't get scratched. Seeing this and feeling empowered, Garou went to show Tareo how powerless heroes truly are.
He began to charge his body as it was encased in a singularity, before unleashing another extremely powerful attack, called Life Eradication Fist, Mark: Gamma Ray Burst, towards Saitama. Now Saitama realized that if any attack grazed the ground it would destroy the planet. So, in an attempt to save it, he decided to jump high into the air to bring the attack away from the ground.
However, Garou thought he was attempting to dodge it by jumping. Because of this, the attack directly hit and completely engulfed Saitama in a beam of the universe's highest level of radiation, sending him off the planet at literally the speed of light itself, if not faster.