Fume Fume no Mi

Introduction
The Fume Fume no Mi is a Paramecia-type Devil Fruit that makes its user an Immortal Human, allowing him to regenerate any wound within seconds, be immune to any toxins, and be unaffected by age. While the Gura Gura no Mi is hailed as the strongest Paramecia-type Devil Fruit, the Fume Fume no Mi is rumored to be the most durable. Its user is Oz Luxor.

Strengths and Weaknesses
The Fume Fume no Mi allows its eater to regenerate any wound within seconds and be unaffected by age. The capabilities of the user's regeneration are boundless. Its user can regenerate from a single cell within seconds, and no matter how gored or distorted they end up being from an attack, they will consistently regenerate back into their original form. Even when struck by Haki, the user's rate of regeneration will be unaffected because the user's body is not directly linked to their devil fruit. Additionally, its user is immune to toxins. Anything toxic that the user ingests will have absolutely no effect on them. Finally, its user will continue to be the same age at which they ate this Devil Fruit, allowing them to live for hundreds or even thousands of years as long as they do not get in the way of harm.

However, to balance this extremely powerful regeneration, there are multiple drawbacks. Firstly, the user must breath, eat, and drink in order to regenerate. Although they can still regenerate from wounds being asphyxiated (e.g. drowning, strangling, poison), they will no longer regenerate once they run out of oxygen. Furthermore, the user must not be starving or dehydrated; otherwise, their rate regeneration will slow down. Secondly, the user is still able to succumb to pain and tiredness. If they suffer from too many wounds, their brain will automatically enter a coma as a danger measure, and regenerating too much will cause the user to faint from tiredness. Although the user can still regenerate while asleep or unconscious, doing so would only increase the time they spend asleep or unconscious. Thirdly, the user has no real super human strength; simply trapping the user might be more effective than knocking them out or killing them.