Cauldron Strength Immortal Gu

Yao Huang bids three items: Kindness Thought Gu, an incomplete wisdom path inheritance, and twice the immortal materials, and wins the auction. He holds the Gu at rank six and plans to raise it to rank seven to improve his odds when refining resurrection from the dead Immortal Gu. He needs a formless vessel for that refinement; phantom path would be best, then strength path, and Cauldron Strength fits that need. The strength cauldron is formless and ethereal: it has no five elements, light, or darkness in it, yet it can still defend against attacks, which makes it a top tier vessel for Gu refinement. ^{ch. 757}

In Yao Huang grotto-heaven, a large cauldron made from cauldron strength Immortal Gu floats before him while he melts immortal materials inside it for that same refinement. ^{ch. 1144}