Haki is one of the most important powers in the world of One Piece. Properly explained to the fans by the legendary Silvers Rayleigh shortly before the two-year time skip, Haki is described as a power that dwells within everyone in the One Piece world, however, only a few are able to make use of this ability. There are two types of Haki, often called its "Colors," which most users of this power specialize in generally.
The Color of Observation, also known as Observation Haki, is a power that resembles sixth sense and allows a user to do extraordinary things such as use precognition, judge the intent of a person, measure power levels, sense their presence, among many other things. Meanwhile, the Color of Armament, or Armament Haki, allows a person to use their spirit as armor to increase their attack power as well as defensive ability. While both Armament and Observation Haki are incredible powers, the one that rules above them is Conqueror's Haki, which is also the most dangerous type of Haki in the story so far.
What Conqueror's Haki Is And Its Abilities
Unlike Armament and Observation Haki, Conqueror's Haki doesn't exist within everyone in the One Piece world. Only a select few people are born with this ability. According to Rayleigh, this power is incredibly rare and only one in a million people can make use of it. Conqueror's Haki allows people to impose their willpower on others, knocking them out in the process. It can also be used to make animals submit to the user and tame others freely, making it quite a dangerous ability. However, the basic usage of this power isn't nearly as special. In fact, those who possess a basic level of Conqueror's Haki simply don't have any advantages in a fight against those who don't. This is because Conqueror's Haki's basic stage is just a big advantage against the weaker opponents. Those who are half decent in terms of strength usually survive the effects of Conqueror's Haki quite easily.
However, with the Wano Country arc, Oda introduced the true power of Conqueror's Haki which has completely altered the power system in One Piece. In Wano, Luffy fought Kaido and in Kuri for the first time and was knocked out by him in a single attack. Weeks later on the rooftop of Onigashima, Luffy was once again hit by a powerful technique, however, this time, he figured out the secret to Kaido's power; Conqueror's Haki.
According to Luffy, Kaido used Conqueror's Haki to coat himself to get stronger, very much like people do with Armament Haki. Being the genius that he is, Luffy attempted to coat himself in Conqueror's Haki immediately and was able to fight against Kaido on an equal footing for a while, to everyone's surprise. Moments ago, Luffy's attacks were simply too shallow to damage Kaido, however, with Conqueror's Haki his regular attacks were powerful enough to knock him down to the ground.
According to Kaido himself, this ability is something that only very few people in the One Piece world can use properly, which is why even though Luffy used it, his usage was considered to be quite crude initially. Despite that, however, it was a big step up to the next level for Luffy as this power is what the greatest of people in the One Piece world use. While it goes without saying that regular Devil Fruit abilities, along with Observation and Armament Haki, are incredible assets, Conqueror's Haki is one of the greatest powers that one can have.
Why Conqueror's Haki Is A Game-Changer
With the way Wano Country has gone, it is quite clear that the characters who possess Conqueror's Haki have a major advantage over most of those who don't. Without Conqueror's Haki, Oden likely couldn't scar Kaido, Zoro wouldn't be able to do the same and Luffy's attacks would still have been way too shallow. With Conqueror's Haki, however, these characters were able to pull off incredible things in their respective fights.
This also seems to imply that the upcoming antagonists in One Piece could be users of advanced Conqueror's Haki, or Haoshoku Haki, as many like to call it. At some point, Luffy will face off against Shanks, who is likely to be a master of this very power, making him one of the very strongest in the story. Suddenly, a whole new world of possibilities opens up with advanced Conqueror's Haki. Luffy's jump to the next level makes sense now, and at the same time, Zoro's found a way to reach the level of Dracule Mihawk. The source of Gol D. Roger's true strength is also finally explained to the fans.
While only seven people seem to be able to wield the advanced form of Conqueror's Haki, there are several others who likely use it in combat, such as Boa Hancock, Monkey D. Dragon, Shanks, Sengoku, and possibly even Eustass Kid in the future of the story. Others possess the potential to awaken it and be considered among the greatest in the One Piece world such as Sanji, Trafalgar Law, and even the future Shogun of Wano, Kozuki Momonosuke.
Advanced Conqueror's Haki signifies that Luffy is finally on the big stage now and he's worthy of fighting the Yonko. It also implies that the time for the Straw Hat Pirates to train is gone and now, they will finally have to step up and face the final test before they become the greatest crew in the world of One Piece. As for Luffy, awakening advanced Conqueror's Haki means that he's ready to compete with the Emperors of the sea and prove himself to be the greatest of them all. After all the years of waiting, Luffy has finally reached a level where he can be called a man worthy of defeating even Kaido, and eventually become the Pirate King.