Cart Titan

Curse of Ymir. The Titan Shifter possessing this Titan will die 13 years after gaining the Jaw Titan.

Equipped Armament. The Cart Titan can be equipped with numerous items. On its own, its stats don't change, but depending on what it has equipped, it gains different abilities:
     Anti-Titan Artillery: The Cart Titan can hold a massive artillery cannon that requires a crew of 3 to operate. The crew can use their actions in conjunction with the Cart Titan's action to make an attack with the cannon.
     Machine Turrets: The Cart Titan can hold an armoured pod on its back that has automatic turrets manned by a 5 person Panzer Unit. The crew can use their actions in conjunction with the Cart Titan's action to make up to five attacks with the turrets. 
     Storage: The Cart Titan can carry up to 3,000 lbs. of equipment on its back without becoming encumbered.

Regeneration. As long as the Titan has 1 hit point, it regains 15 hit points at the start of its turn. The Titan Shifter within the Titan's body doesn't benefit from this trait, but regrows any lost body parts while inside the Titan.

Titan Steam. A Titan gives off a large amount of heat, and it produces steam around its wounds as it regenerates. The area around any open wounds the Titan has are lightly obscured by this steam, and upon death, the Titan's corpse is moderately obscured until the entire corpse evaporates.

Transformation. A Titan Shifter can use their action to transform into a Titan, in this case, the Cart Titan. The Titan keeps the Titan Shifter's Intelligence, Wisdom, and Charisma scores (the above scores are placeholders), as well as the Shifter's alignment. When the Titan dies, or when the Shifter takes an action to end the transformation, the Shifter is ejected from the Titan's body, which instantly drops to 0 hit points and begins evaporating, unless the Shifter rejoins their Titan body within the next minute.

Weak Point. The Titan's weak point is its nape. A creature can target the nape, which has an AC of 19 and 25 hit points. If the attack against the nape misses, it misses the Titan altogether. The nape does not benefit from the Titan's regeneration trait, and the Titan dies if the nape is destroyed. Any damage done to the nape is done to the Titan Shifter within the Titan's body. If the Titan Shifter dies, the Titan dies.

Multiattack. The Cart Titan can make two melee attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 19 (4d6 + 5) piercing damage, and the target must make a DC 18 Dexterity saving throw or be grappled by the Titan (escape DC 18). Alternatively, the Cart Titan can store items or creatures in their mouth without dealing damage, as long as they are size Large or smaller.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 23 (4d8 + 5) bludgeoning damage.

Artillery Cannon (Anti-Titan Artillery Only) Ranged Weapon Attack: +9 to hit, range 1,000 ft., one target. Hit: 55 (10d10) piercing damage.

Machine Turret (Machine Turrets Only). Ranged Weapon Attack: +9 to hit, range 200 ft., one target. Hit: 22 (4d10) piercing damage.

Restore Transformation. As long as the Titan Shifter has more than half of their maximum hit points, the Titan Shifter can move up to their movement and transform into the Cart Titan again once the Cart Titan is reduced to 0 hit points.