Abyssnium

A living material, the abyssnium is more akin to a concentrated mass of flesh and bone with a great amount of protection both magical and physical. If made into armor, the armor would be sentient and would constantly seek control over the wielder, demanding offerings in way of food or flesh to sustain its strength. For all these reasons and many more, it is thus highly illegal and heretical material.

Belaria's armor contains a bit of it, and was initially just a piece of Genghis-Khan's armor. But after being fed and merged with a form-fitted armor of her own, it has fully adapted to suit her needs.