Haki

You can find the haki seller(old man/Silvers Rayleigh) at buggy island, he sells soru(Shave), Armament Haki, Observation Haki, and Geppo(Moon/Skywalk).

Armament Haki: This increases your damage by a lot on every weapon and can be used to hit logia fruit users, you can level it up by killing npcs and gaining mastery(top mastery is unknown and uncheckable).

Observation Haki: lets's you do 2 things. 1. see your opponents aura(useless) and 2. dodge your opponent without taking any damage. it starts with 2 dodges but increases the more you use it up to 8 dodges.

Soru(Shave): This allows you to almost instantly travel long distances and looks like teleporting but is just very fast movement.

Geppo(Skywalk/Moonwalk): this allows you to jump multiple times mid-air, letting you get to place easier and faster. when combined with Soru, you can escape almost any situation against a non-devil fruit user(necessary if you don't have a Logia Fruit)