Attack Titan

Transformation. A Titan shifter can transform into a Titan, in this case, the Attack Titan. When the Titan shifter in human (or humanoid) form has a purpose in their heart and damages themselves, he or she shifts into a Titan. The Titan forms out of air and manifests in seconds. The shifters Intelligence, Wisdom, and Charisma scores stay the same (the ones in the stat block are from the Eren, the shifter from Attack on Titan). Once the Titan shifter wants to revert back to humanoid form, he or she will pop out of the Titan's nape, and the body will slowly melt into steam.

Curse of Ymir. 13 years after its first transformation, the Titan shifter will die. Only a wish spell can prevent this from happening.

Siege Monster. The Attack titan deals double damage to objects and structures.

Regeneration. The Attack Titan recovers 20 hit points at the start of each of its turns. The humanoid inside it also regenerates half of these hit points. If the Attack Titan takes any form of damage to the nape of its neck, this trait doesn't function at the end the Attack Titan's next turn. The Attack Titan only dies if the humanoid inside it dies.

Weak Point. The nape of the Attack Titan's neck is a weak point. An attack which specifically targets the Attack Titan's nape deals damage to the person inside (usually a commoner unless otherwise specified by the DM). If the person inside dies, the Titan dies instantly. You must climb up the Attack Titan to the nape with a Melee attack, or you can try to shoot it with a ranged weapon at disadvantage.

Punch. Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 63 (8d12 + 9) Bludgeoning damage and if the target is Huge or smaller, they must make a DC 22 strength save or be knocked prone.

Kick. Melee Weapon Attack: +14 to hit, reach 25 ft., one target. Hit: 75 (12d10 + 9) Bludgeoning damage, and if the target is large or smaller they must make a DC 22 strength save or be launched 20 ft.

Bite Melee Weapon Attack +14 to hit, reach 10ft., one target. Hit 63 (8d12 + 9) Piercing damage, and If the target is large or smaller it is restrained.

Focused Regeneration (Recharge 5-6). The Attack Titan needs to be ready to battle at any time, and because of this, has an increased healing factor. As an action, the Attack Titan can regenerate twice the amount of hit points it normally would have been able to that turn.

Roar (recharge 6). The Attack Titan screams very loudly, making all targets within a 60 ft. cone from the Attack Titan's mouth make a DC 22 Constitution saving throw. On a success, they are frightened for for 1d2 hours.