Runic Fang

To obtain a Runic Fang you'll need to find and destroy the Ruin Serpent on any World Level. The higher your World Level, the higher your chances of receiving multiple materials at once. To receive them you'll need to spend 40 Resin each time you defeat this Boss.

You do need to complete The Heavenly Stone’s Debris World Quest in The Chasm to unlock this boss. Refer to the image below for its location:

A “fang” with which the mysterious, snakelike machine of old dug into mountains’ depths. There are many ominous runes carved on it. It is said that giant serpents lurk in the dark fissures deep beneath the ground. Burning with eternal resentment and malice toward the world above, they throw themselves into digging great tunnels, yet none know what their malicious purposes are…