The Fruits weakness can also be his greatest strength. When Nero uses his Devil Fruit for too long, he goes into Berserker Mode. When this mode is active it seals off Nero's nervous system, making him immune to pain and it's natural limitations. This ability allows Nero to fight at his full potential, boosting his power and speed at the risk of damaging his own body. With his mode his single punch is powerful enough to destroy a mountain, though the force can break his own arm, but the Devil Fruit will force the scales to pin the bones and muscles back into place. However, this does not actually heal Nero, it just holds him together. This is dangerous because even though he wont feel pain, it doesn't mean he's invincible. Also, this causes Nero to give into his inner demons and lose all se