Bu Fang's question was rather outside of Tang Yin's expectations because it lacked common sense.
The Thunderfire Spirit Pig was a sixth grade spirit beast and was already considered the strongest within the outskirts of the Wildlands. Relatively speaking, it was also an ingredient with the highest grade. If they wanted to find an ingredient of a higher grade than the Thunderfire Spirit Pig, they would need to enter the inner layer of the Wildlands.
The inner layer of the Wildlands was an extremely dangerous place to them. Tang Yin was a sixth grade Battle-Emperor while Lu Xiaoxiao was only a fifth grade Battle-King. If they entered the inner layer at their level, there was very little chance for them to survive if they encountered any spirit beast.
The reason was the weakest of the spirit beasts within the inner layer was already sixth grade, while seventh and even eighth grade spirit beasts could be occasionally encountered.
