That moment is in Impel Down. After Buggy mistakenly reveals the truth behind the armband, Luffy decides to give him the arm band in advance for helping him. On Level 2, Buggy and Mr. 3 along with the inmates on that level continue on, as Blackbeard broke through Magellan's poison blocks on his way down, allowing them to escape.
This, however, made Bon remember about Iva, the person that he also wishes to meet (and save) down in Level 5. Saldeath rallies his security force to go after Luffy forcing him to fight a few until the Sphinx recovers and comes after him as well. After a bit of unusual chatting among one another on what to do next, they decide if they've already been spotted, they might as well call a truce, team up, and raise a ruckus.
Hannyabal tells the guards to go help capture Bon Kurei which they comply. Just as they are about to turn back, they run into Crocodile (much to Mr. 3 shock). He then proceeds to head down to said level with his two cohorts and, as he was still assuming Hannyabal's form, was able to gain access to the keys meant for the cells in Level 5. Before the beast can bite into him a voice catches its attention. But also no ships as well, Crocodile realizing that Magellan sent the Marine ships away to prevent the prisoners' escape. On the ship, the Marines attack Crocodile and Mr. 1 full force but are easily decimated within seconds. This throws Jinbe into a panic as he tells Luffy they have to get topside straight away as they have bigger problems than the warden. As he does so, he remembers a promise he made to Luffy to live a life without regret and to one day go out at sea to live a life with more freedom then anyone. Luffy tries to get some distance but Magellan breathes out a mist into air which the warden calls Poison Cloud, making Luffy's vision hazy and causing him to lose his hearing. But Blackbeard summons a black whirlpool sucking Luffy toward him and slamming him into the ground. Blackbeard explains he found out about Luffy after he defeated Crocodile and due to the newly created open seat in the Shichibukai, Blackbeard figured it would be a perfect way to to make himself known to the World Government. Luffy then inquires about the person who Bon is trying to meet which Bon answers is the queen of Outside, Boa Hancock and Momonga have left the prison and are heading back to their Marine ship via a ferry. While the newbie manages to win, a minotaur-like figure beats them both with his club then throws them into a cell where a monstrous being attacks them. Crocodile surprised Luffy actually bled from the attack since he's made of rubber. Throughout this, Bon has hidden himself, convinced that Luffy cannot win, as Magellan is known to silence even the most ultimate of prisoners.
Over time, he has become incredibly powerful and is capable of defeating even the strongest of Pirates in battle. On Level 6 Ace demands to know what's happening upstairs but the guards state it's nothing. Four hours remaining before the deadline of such. They tell them to cause a riot throughout all of Impel Down, grabbing keys and unlocking cages as they go to keep the security forces occupied.
Furthermore, Shiryu is the current user of the Suke Suke no Mi after having killed Absalom, its former user.The son of Gol D. Roger and the former Second Division Commander of the Whitebeard Pirates, Ace was easily among the strongest characters to step foot in Impel Down.
When asked why to the guards, they state that he disappeared presumably snatched away by some unknown figure that has been doing so to other prisoners on the level which they dub as "demoning away" (interestingly said prisoners were on the verge of freezing to death when they disappeared). Furthermore, Ace was already a user of all three Haki types (Observation unconfirmed) by the time of his death, which further boosts his rank among the prisoners. Iva shrugs this off and tells the others to follow after him. Soon the Okama army follows with Bon quickly kicking Buggy and Mr. 3 for their earlier abandonment.
Shiki was someone capable of rivaling Gol D. Roger, and it's not a surprise that he tops the list of the strongest event Impel Down prisoners.Rei Penber is an avid fan of anime and manga. This category is for people who are currently imprisoned in Level 6 of Impel Down. Even the three they've recently downed they will soon be back on their feet as well but Crocodile is more worried about Magellan than them. Inazuma returns Luffy's clothes and straw hat but mentions that he has not fully recovered yet and should take a day to rest. Magellan, too, is stunned as the Gates could only be opened by Impel Down.
Buggy feels guilty for lying to Luffy but he decides nonetheless to escape from Luffy.