Haki/Busoshoku Haki

Busoshoku Haki allows the user to create a force similar to an invisible armor around themselves. Similar to Tekkai, this allows the user to defend against attacks that would otherwise cause them harm. Only significant physical force can overcome this defense.

Naturally this "invisible armor" can be used as a weapon to strike others with. It can be used to augment the user's own attacks, projected ahead of the user as pure brute force, or imbued in weapons to increase their effectiveness. Any attack enhanced by Busoshoku Haki hits immensely harder than it would normally be without it.

This type of Haki also has the ability to bypass the powers of a Devil Fruit user, touching the "substantial body" beneath whatever protection the fruit provides, such as the case of body-altering Devil Fruits such as Logia users. However, unlike seastone it does not negate a user's Devil Fruit powers, allowing them to defend themselves, and continue fighting normally. By the same effect, this Haki can also be used as a higher level of offensive, more so than just bypassing a foe's Devil Fruit powers. It can be used to harden parts of one's body, turning the area black, making the user denser and more formidable, and giving their attacks greater power.

It's first used by Sven R. Pocalyptic when he applied Busoshoku Haki into a cake and used as a weapon during his prison break.

Although most other known users of this Haki have yet to be seen using this, only implied, it would seem that Vice-Admiral Coza seems to be the most effecient in using this; having such an implied high level of Haki that he can use a form of it known as Vulcanization, where a user can harden their own body so much that they take on a black/greyish color to it.

Known Busoshoku Haki Users
These are the confirmed people who are known to have used this Haki type before