Episode of Sabo: Bond of Three Brothers - A Miraculous Reunion and an Inherited Will - S0.E12

After Ace's death in the Marineford War, which is seen in flashbacks, Sabo appears at his grave. He later arrives in Dressrosa to investigate a weapon smuggling, where he is informed that Doflamingo is holding a tournament at the nearby coliseum with Ace's Flame-Flame devil fruit as a prize.