Episode 668 - Luffy's Supreme Heritage! The Decisive Clash for the Pirate Monarch's Crown

Episode 668
Luffy’s Ultimate Legacy! The Final Battle for the Pirate King's Throne
Japanese: ルフィの究極の遺産！海賊王の座をかけた最後の戦い
Rufi no Kyūkyoku no Isan! Kaizoku-Ō no Za o Kaketa Saigo no Tatakai

The Straw Hat Pirates engage in an epic battle against the powerful pirate crew. As the fight reaches its peak, the crew is forced to make an unexpected alliance with a group of former enemies. Together, they fight to protect the Grand Line from being consumed by the forces of chaos. The episode ends with the pirates narrowly escaping their foes.