This ability allowed Luffy to go toe-to-toe with an Emperor without relying solely on Gears or pure physical stamina. It was the missing piece of the puzzle.
Luffy's journey with Conqueror's Haki began during his childhood, when he was exposed to the intense emotions and strong wills of his idol, Shanks, and the other members of the Straw Hat Pirates. However, it wasn't until he faced Vergo, a powerful Marine officer, that Luffy's Conqueror's Haki first manifested. This initial display of Conqueror's Haki was largely instinctual, and Luffy struggled to control and understand his newfound ability.