Go Gear Fourth

When Luffy goes Gear Fourth during the game he will undergo a transformation where he will gain the strength of Armament Haki and the speed of Observation Haki simultaneously, this will enable him to deal heavy damage to enemies in a short period of time. Once in this form Luffy is invincible and will remain so until the form is depleted. One of the big perks of going Gear Fourth is that it gives Luffy the ability to travel by air.

Luffy does not have Gear Fourth at the start of One Piece World Seeker, it needs to be unlocked by progressing to a certain point in the game. Once Luffy reaches Chapter 8 you will be told that there is a Navy Admiral approaching the town. When Luffy confronts him he discovers that it is Fujitora and after a brief cutscene Gear Fourth will be unlocked. Pressing 'Up' on the D-pad will activate Gear Fourth to transform Luffy, the amount of time he stays transformed is dependant on how many tension guages you have filled up. If you have one tension guage filled up Luffy will remain in Gear Fourth for about 20 seconds, two guages will allow him to stay transformed for 40 seconds and having three gauges filled up will grant Luffy a full minute. To fill these guages up so you extend Luffy's time in Gear Fourth you need to attack Fujitora with a series of combos without sustaining any damage from him in return.

Once you have used and depleted Gear Fourth Luffy will be fatigued and you will be unable to refill his tension gauge for a short period of time. Gear Fourth will not work in cramped confined areas such as a ship deck or alleyway so you need to be aware of whether there is enough room before you attempt the transformation.