Eren Yeager's powers and abilities
Martial Arts
Originally, Eren's only noteworthy trait was his natural physical strength, which stemmed from having to defend his friend Armin from bullies who were bigger and stronger. As he grew and joined the 104th squad, he trained extensively in hand-to-hand combat. After additional training with Reiner and Annie, Eren's prowess and skill set diversified, including the use of punches, throws, grappling, and submission locks. He had the best scores for hand-to-hand combat of the entire 104th graduate squad. While hand-to-hand fighting would appear useless due to the massive physical differences between humans and Titans, these skills gave Eren a powerful edge when fighting other Titans in his own Titan form.
Vertical Maneuvering Equipment
Though having little talent, through intense training and effort he managed to gain a considerable amount of skill with the equipment. Even so, Eren was not completely lacking in natural aptitude. While using the damaged equipment, he had managed to stay upright for a short amount of time, which the instructor, Keith Shadis, said was an incredible feat, and balanced with ease when using proper gear. The fact he graduated as the 5th best of the 104th graduate squad, even before Jean Kirstein, who was top of the class in mobility with the gear, implied that he had considerable combat skill with the maneuvering equipment.
Though Eren was not shown using the equipment as often as other members of the Survey Corps, he was able to hold his own against the Colossus Titan until the Titan disappeared, almost reaching the nape twice. He was even capable of killing a Titan on his own not too long after joining the Survey Corps. His most significant use of maneuvering equipment was shown during the Battle of Shiganshina, where he was able to use it to cut Bertolt Hoover out of the Colossus Titan's nape while he was distracted by his hardened Titan form, despite being exhausted.
Attack Titan
After the fall of Wall Maria, Grisha found Eren in a refugee camp and brought him into a nearby forest. After giving him the key to the basement, Grisha injected a struggling Eren with a serum, which transformed him into a 4 meter Pure Titan with short rugged hair and a skinny body. This Titan ate Grisha, giving Eren the powers of the Founding Titan and Attack Titan. Years later, during the first Battle of Trost, Eren was eaten alive by a Titan, and inside the stomach-like cavity saw other fellow recruits lying dead/dying, one wanting her mother before sinking in stomach acid. The sight combined with intense feelings of desperation and his drive to exterminate all Titans awoke his ability to transform into his Titan form for the first time.
In this form, Eren is a 15 meter tall Titan, with shoulder-length black hair, pointed ears, a long nose, and a gaping, skeleton-like maw lacking lips. Unlike most other Titans, his Titan form is considerably more muscular and defined; making him much stronger than even similar-sized Titans while his intelligence and military training, allow him to out-maneuver and dispatch entire groups of Titans with ease. A transformation takes a heavy toll on Eren�??s body and requires large amounts of stamina. As a result, he has displayed several symptoms when he over-exerts himself such as nosebleed, pale skin, and labored breathing. In some cases, Eren is rendered unconscious for a short period of time after a Titan transformation.
Initially, Eren has no control over his actions when he first transforms into a Titan and is unable to remember any actions that occurred during the first Battle of Trost. He is in a �??dream-like state�?� and fails to remember how to transform in the first place. However, Eren recalls fragmented memories of his father by seeing the key to the basement of his old home and is able to successfully transform to protect Armin and Mikasa from certain death. It has been shown that with more transformations, Eren retains more of is intelligence being able to form rational thoughts. At the beginning, during the second Battle of Trost, Eren in his Titan form attacks Mikasa but ultimately plugs the hole in Trost's gate after Armin forces him to wake up. His Titan form, combined with his growing experience and his hand-to-hand combat skills, allowed him to kill over 20 Titans in his first transformation and later manage to overpower and nearly kill the Armored Titan.
Eren, like all others with the power of the Titans, must physically harm himself (or suffer some kind of injury) in order to transform into his Titan form. However, lack of a determined goal and resolution for it inhibits his ability to transform as shown when he cannot transform at first to confront Annie Leonhart. Within Titan transformations, he has displayed the ability to partially transform, as shown when he protected Mikasa and Armin from a cannonball by forming the upper torso skeleton, complete with arms and a skull with some muscle tissue.
Enhanced Strength
As a result of Eren�??s Titan form being much more muscular than other Titans, he is much stronger in terms of physical strength. During his first transformation, Eren was able to decapitate a 15m Titan with a single punch and kill a 7m Titan with little effort. With both arms lost, he was also strong enough to bite into the neck of a large, abnormal Titan that ate Thomas and lift it up above his head. With enough force, Eren was able to throw the abnormal into another Titan hard enough to knock them both into a building. Against the Female Titan in the Titan Forest, Eren�??s Titan form had enough physical force to leave large craters in the ground, as well as lift the Female Titan into the air with a punch. Ultimately, Eren�??s greatest display of strength was when he lifted a giant boulder, albeit with difficulty, carry it across a large distance, and slam it down to seal the hole in Trost's gate, producing a large shock wave.
Enhanced Endurance
Perhaps Eren's most notable trait of all is his ability to maintain levels of activity for an extended period of time. His first transformation carried on long enough to incapacitate 20 Titans in total. In battle, even after receiving massive amounts of damage from the Female Titan, Eren can carry on fighting, despite the handicaps that he suffers. He was also able to fight against the Armored Titan for a period of time and gain the upper hand. Eren�??s endurance in his Titan form was enough to allow him to sustain the effort of hoisting a huge rock on his back, carry it over a large distance, and seal the hole in Trost's gate shortly before collapsing. In Marley, Eren displayed exceptional improvement in his durability. He could transform into a Titan three times in one battle, surprising Galliard.
Hardening
After drinking a bottle labeled "Armor" from Rod Reiss's bag, Eren's Titan form gained the ability to harden its body, as well as create a web of pillars that appear to originate from his Titan body. The hardened pillars are incredibly durable, capable of preventing a cave-in, as well as shielding Squad Levi from the heat of Rod Reiss' Titan form. The constructs, as well as Eren's Titan, also retain their durability and hardened state even after he has been separated from his Titan body. After two months of training with Hange Zoë, Eren is able to seal a cave with his hardening powers and reinforce the hole the Colossus Titan left in Trost. However, the constant use of this power can overwhelm Eren and make him weak. By focusing his hardening in one place, it gets even stronger. Focusing on his fists gives Eren a hardened punch, capable of easily breaking the Armored Titan's face armor. In Marley, Eren's improved hardening abilities let him harden his forearm fast enough to block a hardened spike from the War Hammer before it could pierce his nape.
Regeneration
Eren�??s Titan form has demonstrated the ability to automatically heal any injury sustained in battle and also to regenerate entire limbs. Unlike Annie Leonhart, Eren has not shown the advanced ability to focus regeneration on one wounded area of his Titan form. His healing factor was fast enough to heal an entire lost hand in mere seconds to an entire arm in minutes. This ability is useful to Eren as, when he fights, he often loses entire limbs in his Titan form. While in his human state, Eren can also regenerate entire lost limbs, as seen by regrowing an arm and leg he lost to Titans. When captured by Reiner and Bertolt in the Titan Forest, Eren was seen regenerating his lost arms after he lost a fight in his Titan form. During his infiltration mission in Marley, Eren has mastered this ability to the extent that he can restrain the regeneration of his left leg in order to disguise himself as an injured soldier.
Future Memory Inheritance
As part of the Attack Titan's unique abilities, Eren can reveal his own memories to his predecessors, giving them insight into the future. He gives memories of the future to his father Grisha, selecting the ones that would suit his purpose. By doing so, he indirectly gives his younger self-insight into his own future via Grisha's memories when Eren kisses Historia's hand.
Founding Titan
With the power of the Founding Titan that Grisha Yeager stole from the Reiss family, Eren possesses the ability to control nearby Titans, causing them to relentlessly attack his chosen target. However, this ability can only be used while Eren is in contact with a Titan of royal blood.
The first time he uses it is entirely by accident, by touching the palm of Dina Fritz's Titan, causing nearby Titans to attack and devour her, and setting the same Titans upon Bertolt and Reiner. While it is shown that others with the power of the Titans can sense the activation of his power, it is unknown whether it is possible to use it to influence or control other human-controlled Titans.
Possession of the Founding Titan is the reason many groups have expressed an interest in Eren, including Marley's Warriors in their Paradis Island Operation, and Rod Reiss, the former patriarch of the Reiss family.
Four years after Eren's first, and accidental use of it, Eren is finally able to unlock the full capabilities of the Founding Titan after freeing the soul of Ymir Fritz from the control of her descendants, giving him access to all of the Founder's powers. With the full power of the Founder, Eren is able to control all of the Wall Titans, create a skeleton that towers over all of them, and can telepathically communicate with all of the Subjects of Ymir.
War Hammer Titan
Eren obtains the power of the War Hammer Titan during the Raid on Liberio by devouring the younger sister of Willy. He is capable of using the War Hammer's abilities to create weapons and more by controlling Titan hardening.
