The Challenger-class Player's Regression

'''He was one of the five Grand Masters. But with a broken body, he could do nothing but watch as Earth met its demise. “Even if I die…! I’m taking you bastards down with me!” In his final moment, he poured everything he had into a single strike against the calamity. [Congratulations! Your rank has been promoted to ‘Challenger’!] [The first Challenger has been born!] He had finally achieved the rank of the first Challenger. However, as he was on the verge of death, he closed his eyes, leaving behind only regret and lingering longing…. [Return once more to this place. Become the Challenger.] [For you possess the potential.] He returned to the past. His body is intact, and his plan ...