Logia

Logia is a type of Devil Fruit. It is commonly characterized by giving it's user the ability to turn into a natural element.

Effect
With these fruits, the user may actually become a natural element. They are neither totally human nor element in their default state. Logia users can turn completely into their element if they want to. This is often used for crossing great distances fast, or avoiding blows should their weakness be discovered.

Strengths
Logia is the most powerful of the three groups as well as the rarest. Even in their default states, Logia users are near invincible (even to each other), taking no damage from physical attacks. For example, if their element is not solid, a blow can pass right through the user while he maintains the rest of his body, and can even hold onto objects at the same time. Even Aokiji's solid ice body will re-form instantly if broken. If the user trains their new powers, they can manipulate anything related to their element. Logia users can tap unlimited amounts of their elements from their own bodies, and the "extracted" element can be manipulated however the user wants. Most Logia seem to have the ability to fly (with the probable exception of Aokiji and Blackbeard) by turning their whole body in their element or just the lower half of the body (this is shown being done by Ace, Crocodile and Smoker).

Weaknesses
The main method of causing harm to a Logia user (aside from exploiting the effects of the sea and Seastone) are natural weaknesses which, when exploited, can ultimately lower a Logia user's power-- for instance, the electrically powered Enel can be hurt by insulating substances like rubber which also makes the insulator immune to his attacks, and Sir Crocodile, made of sand, can be struck if his body is dampened first. The only other time a physical blow may hurt the user is when he or she is caught off guard, as this gives the user no time to mentally change into their elemental form. However, the powers of a Logia can be trained to counter this problem, an example being Sir Crocodile's, who honed his abilities to the point of being able to turn on his powers as a reflex to a blow.

Other information
Logia is the rarest of the three groups of Devil Fruit. Logia users cannot control their elements if it is in another state of matter. But they may use their surroundings to generate it. These Devil Fruits are also not limited to the classical elements: fire, water, earth, air and aether but includes physical states like smoke and sand. There are two types Solid (something a person could hold like Sand or Ice) and intangible (something that could not be held like Smoke or Fire). Furthermore, their ability to move out of harm's way using their powers seems to serve as a defense-mechanism of sorts designed to save them from otherwise life-threatening attacks (i.e. getting cut in half), and if not trained properly (like Crocodile's), could be easily bypassed by non-lethal physical attacks. This was demonstrated by Luffy in Nanohana where he used a Gomu Gomu No Rocket to propel himself inside a restaurant, sending Smoker and Ace (both Logia-type users) flying.

List of Known Logia Fruit

 * Moku Moku no Mi
 * Mera Mera no Mi
 * Suna Suna no Mi
 * Goro Goro no Mi
 * Hie Hie no Mi
 * Yami Yami no Mi
 * Ame Ame no Mi
 * Toro Toro no Mi
 * Basa Basa no Mi

Unknown

 * Kizaru's light based Devil Fruit.