The Second Component of the Longgui Bulwark Armor was called as Magma Hardening.
In it, the user had to change the balance of the elements by removing the fire element completely. This would allow them to condense an armor around them which would be wholly composed of Metal and Earth elements.
If one were to convert it into a ratio, it would be a 0:1:1 ratio between fire, metal, and earth elements. This would turn the mixture rigid and therefore, become defensive. But one needed to be careful about how they actually condensed the armor.
If they didn't do it in the right way, they would simply end up forming a solid construct around them, turning themselves into rigid statues. This would defeat the purpose of the skill and leave one with no mobility.
Lin Mu finally starts with the new technique.╰(*°▽°*)╯