Episode 325

"The Most Evil Ability! Blackbeard's Darkness Attacks Ace" is the 325th episode of One Piece.

Summary
Three days before Luffy leaves Water 7, Ace finally catches up to Blackbeard on Banaro Island, but his attempt to fight him reveals Teach's darkest secret: the control of the Yami Yami no Mi, the most evil of Devil Fruits. As fire and dark gravity collide, the island is destroyed. The outcome is unknown, but Ace's hat is shown lying on the ground. It is said that the fight between them is the trigger for a great event yet to come.