WARNING: The following contains spoilers for One Piece, Chapter #996 by Eiichiro Oda, Stephen Paul, and Vanessa Satone, available in English now from Viz Media.
To say a lot happens in One Piece Chapter 996 would be an understatement. Many pieces are making their last moves across a board before the final battles begin. One clear example of this is in how many characters are desperate to reach the rooftop and face Kaido.
With some help from Franky in his Shogun Mecha, Yamato was able to save Momonosuke and Shinobu from Sasaki. While this is taking place on one of the towers of Onigashima, the characters in the palace have begun their final pushes towards the rooftop.
On the third floor, Eustass Kid and Killer are getting past the assortment of Kaido's men. Thanks to Kid's magnetic Devil Fruit powers, he's able to attract all of the footsoldiers' weapons, leaving them defenseless as he bulldozes through with Killer. It seems Kid is going to need every weapon he can get if he's going to face the world's strongest pirate, Kaido.
Big Mom finally makes it back inside the performance hall where the Ice Oni invasion is taking place. She isn't interested in dealing with the stragglers still here like Zoro, Robin or X Drake; instead, she's trying to make it to the rooftop to assist Kaido. It's a breath of relief to know the remaining Straw Hats are not her target, but if they simply ignore Big Mom, they're just giving another ally to Kaido. Zoro could try to step in and stop her, but that would leave the Ice Oni virus unchecked yet again.
Climbing to the second floor are Luffy, Sanji and Jimbei. The cook insists to the other two Straw Hats he's hearing some kind of voice, but neither Jimbei nor Luffy are reacting to it at all. Sanji says it's coming from the third floor, so this could be his Observational Haki. However, when he hears the very "cutesy" way the voice is speaking, Sanji reacts to fear and shock.
The only person who could make Sanji react in such a way would be Emporio Ivankov of the Revolutionary Army and the Kammabakka Kingdom. Iva hasn't been seen must since the time skip, but the Revolutionary Army's base was destroyed by Blackbeard during Whole Cake Island. Why would the Revolutionaries take their fight to Kaido? We'll just have to wait and see.
Unfortunately, things aren't looking good for the Red Scabbards in their fight against Kaido. With a swing of his club, Kaido manages to knock out Kin'emon and Denjiro sequentially. Then on closer inspection, many of the other scabbards like Raizo have fallen as well. Hopefully, Kid or Luffy can reach the rooftop before the scabbards meet their end. An exciting chapter without question as Oda approaches his 1000th chapter of One Piece.