Armored Titan

Transformation. A Titan shifter can transform into a Titan, in this case, the Armored 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 just place holders). 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.

Siege Monster. The Armored Titan deals double damage to objects and structures.

Regeneration. The Armored 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 Armored 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 Armored Titan only dies if the humanoid inside it dies.

Weak Point. The nape of the Armored Titan's neck is a weak point. An attack which specifically targets the Armored Titan's nape deals damage to the person inside. 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.

Multiattack. The Armored Titan makes two punch attacks.

Punch. Melee Weapon Attack. +13 to hit, reach 20 ft, one target. Hit: 52 (8d10 +8) bludgeoning damage and the target must make a DC 20 Strength saving throw or be knocked prone. On a failed save, the target is also pushed up to 10 feet away from the armored titan.

Charge (Recharge 5-6). If the Armored Titan runs at least 50 feet in one direction at something, it can make a body slam attack. +16 to hit. Hit: 74 (12d10 +8) bludgeoning damage, and the target gets knocked prone.