One Piece 519- The King's Desposition

Luffy faces off against Hebihime's sisters Sandersonia and Marygold, both of whom have eaten the Snake Snake Fruit and have changed into giant snakes. The crowd is going wild for the Gorgon sisters, but Luffy just thinks that they are Devil Fruit users and nothing more than that. Before the fight starts, Luffy moves the petrified Margaret and her two friends off of the main level so they won't be caught in the battle.
During the battle, Luffy attacks the two sisters, but his attacks have no effect. The sisters' attacks however deal damage to Luffy despite the fact that he's made out of rubber. Luffy is knocked down by Marygold and then constricted by Sandersonia. Sandersonia explains that since Luffy is weak because he can't use haki. Sandersonia is also able to read Luffy's move and dodges his kick, and then she slams Luffy against the arena floor.
This type is straight-physical attack doesn't damage Luffy, and the young pirate renews his attack but Sandersonia dodges every single one of his punches. Marygold takes advantage by knocking Luffy down with her tail. Luffy barely avoids being impaled by the bladed pit that surrounds the battle arena by hanging on to the arena edge. Hebihime ridicules Luffy as he climbs back on to the arena, and Luffy retailiates by telling Hebihime to shut up. Angered by Luffy's insolence, Hebihime tells her sisters to finish Luffy off. Sandersonia grabs the petrified Margaret and threatens to crush her. Luffy tells the Gorgon sisters to leave Margaret out of the battle, but instead Marygold grabs Luffy and she's going to make Luffy watch as Sandersonia smash Margaret up.
Sandersonia raises Margaret and is about to smash her into the floor. Luffy yells "Stop" with all his might, and this shocks the Gorgon sisters into letting him and Margaret go. Many of the warriors in the audience faint from Luffy's outburst, and the warior who managed to stay conscious realizes that Luffy has the "haoushoku" haki that is found only in one out of a million people. The three Gorgon sisters realizes that Luffy is not a normal guy, and now Luffy is ready to take on Marygold and Sandersonia with all of his powers.