By drinking this shockingly disgusting fruit drink, you gain powers from the world of One Piece!
*Start off as strong as Luffy at the start of the series. You may redesign your appearance right after you drink this essence. You also start off with access to all three forms of Haki although the stronger abilities need to be learned and trained. Your ability to learn and train is enhanced and you will find gains in your abilities to come in leaps and bounds.
*You have access to any known Devil Fruit power and can in fact make your own. You can only access one at a time, although the switch rate is rather quick. New powers must be made in accordance with the rules and types of Devil Fruits, and come with their generic and specific weaknesses. However you can turn DF powers off entirely, and go without any of their weaknesses.
*At any time you may pull a seed out of your pocket or have it appear in your hand. This seed will quickly grow if planted into a strange plant and within a week give you a Devil Fruit based on whatever DF power you choose. This fruit acts like a normal DF and you can make only one copy of a specific fruit at any one time, but if a fruit you make is back in fruit form you can summon it back to yourself.
*You can also temporarily turn off a devil fruit power from fruits you yourself have grown.
*You can transform into a member of any of the many sapient tribes of people that live in OP. From Mer-men to Long Legs to Giants and Minks. And can even turn willing people into other races as well. You are a rather outstanding member of said race in physical abilities and their individual powers.
*Though dreams or meditation you can enter a weird island space filled with poneglyphs and Easter Island heads, these poneglyphs carry the knowledge and memories of the OP world. Everything from Fishman Karate to how to make cyborgs is here. Although finding it and studying it can be a pain. Some poneglyphs are encrypted and need time to translate. Also you can read real world poneglyphs as well.
*You gain a ship you can summon on any body of water that can hold your ship. Its essentially a reskin of the Thousand Sunny with similar capabilities. You can use this ship to travel from any body of water on Earth or wherever you are to the One Piece world. And in time maybe even farther. The ship comes with a small four man core of a nakama. They can be canon or AU versions of people from the series, or even tailored made by you. However starting off they are about as strong as the starting stawhat crew, with you as the strongest person on the ship. How this occurred to someone who started off more powerful is a mystery.