The Cauldron Born are some of the more powerful variations of Darkhearts in existence, being undead skeletons reanimated by the powers of the Black Cauldron with the heart of a slain sacrifice powering them all. They are the primary force for the newly risen 13 Seekers of Darkness, more specifically their lord and master, the Horned King.
The Keyblade Wars
Birth of A New Era
The Chain of Memories/Reversed Awakenings
The Fantasmic Dreamtime
Return of the Keyblade
Most Cauldron-Born are rotting skeletons with slender bone frames and the occasional glowing orb within their eye sockets. The freshest corpses used as Cauldron-Born have "livid" or "pallid" features, "lightless eyes" like stones, and mouths "frozen in the hideous grin of death". They wear studded bronze breastplates, heavy bronze belts, and wield swords and black leather whips. Certain Cauldron warriors, sent on the Horned King's "ruthless tasks" of recon or capture, wear no helmets nor bear shields; while those deployed for battle are more heavily armored and bear both helms and shields.
The Cauldron-Born's greatest advantage is that they are not alive, and thus cannot be killed. They feel no pain or fear or mercy, do not need water or food or sleep, and they never question orders because they possess no soul or memory of who they were in life. Simply put, they are puppets of Marwoleath who will obey his every command. However, the Cauldron-Born are not omnipotent. Their power diminishes the further they get from Annuvin and the Black Cauldron. In fact it is possible for them to stray far enough that they return to a normal corpse. However, it seems they have an innate knowledge of exactly how far they can go before this happens. This limit aside they only have one true weakness, the black sword Dyrnwyn.