Attack on Titan has seen an array of titans. Gone are the days when we harmlessly thought that titans were simply brainless monsters that consumed human flesh. Now that the anime has evolved and expanded, more unique and interesting versions of these titans have been revealed over the course of events.
There are nine special titans with their own respective abilities and appearances, as explained in the anime and manga. However, the least-shown of them is the War Hammer Titan, which we first saw in season 4. So what exactly is this imposing titan, and just how important is it to the series' narrative overall?
Who Is The War Hammer Titan?
After Ymir Fritz's death, her soul was split into nine different special titan forms. The War Hammer is one of them. Its body is covered in a hard white shell that is made by its remarkable hardening abilities. Using this hardening, it can manufacture any weapon imaginable. In the anime, we have seen the War Hammer fight by creating giant pikes, a crossbow, and swinging its titular war hammer.
The human wielder of the War Hammer does not lie in the nape of its neck, however. Instead, a string of hardening matter extends from the titan's foot into the ground below, eventually leading to the body which is encased in an impenetrable crystal. The titan is also seen talking. The drawback with the Warhammer is that it has little stamina. Constantly fashioning weapons in a short time frame will cause the titan to run out of stamina.
The Tybur Family
We first see the War Hammer in episode 6 of season 4 of the anime and chapter 101 of the manga. At the time, Lara Tybur of the Tybur family, a noble Eldian household that hold very high status in Marley, was in possession of the War Hammer. When Willy Tybur declared war on Paradis in front of journalists and politicians from around the world, Eren Yeager transformed into his titan form and killed Willy and other civilians. Lara transforms into her War Hammer form and fights Eren, only to lose to him. Lara Tybur's battle with Eren was her first time using War Hammer in combat. This is inferred from the fact that Tyburs have never sent the titan to enemy soil, as stated by Pieck.
The Tyburs were in possession of the War Hammer during the Great Titan War. They were the first Eldians to assist Marley in this time. When the war ended, the Tyburs lived in Marley as honorary citizens, swearing to protect the country. The Tyburs keep the identity of the wielder of the War Hammer a secret, save for a few Marleyans of high stature.
Eren's Acquisition of the War Hammer
Pretending to be a heavily wounded soldier, Eren quietly infiltrated Marley. During Willy's declaration of war stage production, Reiner and Falco discover Eren's identity in a cellar below. After Eren transforms and kills Willy and other innocent civilians, he fights Lara's War Hammer.
Upon Mikasa's arrival to the field of combat and discovering that the War Hammer sustained no damage from the Thunder Spears, Eren discovers that Lara's body is encased in a hard crystal underground. He subsequently uses the teeth of Porco's Jaw titan to break open this crystal and devour her. He is now the current wielder of the War Hammer, possessing the Attack and Founding Titans, additionally.
The Use of the War Hammer
When Eren is imprisoned in Marely, he informs Zoë Hange that he can use the powers of the War Hammer to break out of his prison cell at any time. He does so and uses the War Hammer's hardening to close off the escape route so that military personnel does not try to pursue him.
In chapter 117 of the manga and episode 17 of season 4 of the anime, Eren creates long spikes from his back to defend himself from Porco's Jaw Titan. He also managed to create giant spikes emerging from the ground, these were able to pierce through Reiner Braun's Armored Titan form. The War Hammer has a very striking appearance, however, Eren's new titan form does not showcase any of the hardened shell that the original War Hammer did.
The War Hammer's Brief Resurrection
Towards the tail end of the manga, the remaining members of the Survey Corps manage to reach Eren in his Founding Titan form aboard Falco's flying Jaw Titan. Using the powers of the Founder, Eren was able to resurrect the bodies of all previous titan forms of the nine unique titans. Generations of old Jaw, Beast, Female and the like were brought back by Eren to aid his fight, even titans belonging to characters we have already seen, such as Bertholt's Colossal Titan. In the same way, all past forms of the War Hammer were conjured, including Lara Tybur's form.