WARNING: The following contains spoilers for Chapter #135 of Attack on Titan, "The Battle of Heaven and Earth," by Hajime Isayama, Dezi Sienty and Alex Ko Ransom, now available in English from Kodansha.
As the fourth season of the Attack on Titan anime begins its journey to the end, Hajime Isayama's manga series is already standing right at the precipice. The remnants of the Survey Corps, backed up by Pieck (the Cart Titan) and Reiner (the Armored Titan), finally made it to Eren's vast Founding Titan body in the last chapter. Now, in Chapter #135, they not only have to face their former friend in "The Battle of Heaven and Earth," but the rest of the Nine Titans atop his spine.
Not only is this a historic battle in-universe but it's the first time we've ever seen the full power of the Nine on the same battlefield. And when we say 'full,' we don't just mean the current holders: every past inheritor is summoned for this epic clash.
As the Survey Corps realize the nature of the army standing in front of them, Connie verbalizes just how terrifying what they're about to fight really is: "This is an army of veteran Titans created only for battle. How are we supposed to fight that?" For Pieck and Reiner, the stakes are more personal as they're literally assaulted by the 'ghosts' of their past Warrior comrades and compatriots. As Pieck takes "decisive" action and attempts to blow Eren up at his nape, her Cart Titan body is skewered by the Tybur's War Hammer Titan; Reiner, meanwhile, is smashed by Galliard's Jaw Titan and then has his Armored Titan body destroyed by Bertolt's Colossal Titan.
The reason why this is possible is that the Nine Titans originate from a singular form -- Ymir, the Founder. Ymir was made into the first Titan 2,000 years ago and when she died 13 years later, that power was disseminated into nine individual ones and divided among her heirs by way of cannibalism. This has been the method of Titan Shifter inheritance ever since. Ymir, liberated by Eren to enact her revenge on a humanity that kept her physically and then spiritually bound for centuries, seems to have a presence in the real world thanks to lending Eren her Founding Titan power, and she uses her connection to her subjects to conjure (from out of the Titan's bones, it appears) every past version of the Nine. As Pieck explains: "It must be possible to resurrect an infinite number of them if you have the power of the Founding Titan."
Through all the nailbiting carnage, it's still a fascinating look back at a history we've never been able to see until now. Only a few of the Nine in the present-day have changed hands, and their forms, while different, aren't often drastically so. In Chapter #135, it's clear the Nine can come in all kinds of shapes and sizes: one looks like a crocodile, another like a Minotaur while one is essentially Marvel's The Thing.
There's also another important piece of information confirmed by the chapter relating to this tour of Titan Shifters through the ages. Armin, spying the child form of Ymir watching the battle, realizes that the Founder is the one attacking them, not Eren. Eren's only mission is to move "forward" by eradicating everything beyond Paradis Island but he wants his closest allies to be safe there once the dust has settled. But when Armin is snatched up and begins to be suffocated by a Titan's tongue, even he starts to question whether or not Eren really does mean them no harm.
The Survey Corps barely make it out of the battle alive (minus a trussed-up Armin) thanks to the Hail Mary arrival of Falco in his now-airborne Jaw Titan form, as predicted, and though they were all willing to go down fighting, surviving the biggest Titan battle in history is a win in itself.
