Small White Rodent

Mu Yu chose to stay at Ku Mu Valley in the end. Lie Shang and company couldn't save Feng Haochen. If he joined them, the only progress he'd make was cultivation. It was highly unlikely he could conquer Third Heaven Palace using sheer brute force. Therefore, he decided to gamble on Ku Mu having some strategy to save Feng Haochen.

"Wh-what functions do c-celestial fiend fruits have?" was the first question Ku Mu posed to Mu Yu every day. Mu Yu would then recite, "Celestial fiend fruits are an herb possessing a myriad of uses. One can cut off a small section to replace the shortage of other herbs during alchemy. It can also reduce the conflicting components of various herbs, thereby allowing said herbs to be combined. It takes a hundred years for two fruits to ripen."

Mu Yu was informed Feng Haochen had to heal his dantian to regain his cultivation. Feng Haochen's dantian was severely damaged due to him sacrificing his cultivation for Celestial Prison. It was also the reason behind his drastic regression in cultivation.

There was a pill called restoring yang pill that could heal Feng Haochen's dantian. To create it, a nine qi soul cleansing flower and dark herb were required. Unfortunately, nine qi soul cleansing flowers only existed in ancient texts for a while now. Ku Mu intended to replace it using a celestial fiend fruit he grew. As such, Mu Yu wanted to slap himself whenever celestial fiend fruits were mentioned.

"You need to find the two on your own. As for where they can be found, I'll tell you another time."

Because Ku Mu forced Mu Yu to learn Profound Formations, as well, Mu Yu shared Feng Haochen was an expert on the topic, only for Ku Mu to rebut, "H-his formations? H-he is an amateur."

The "profound" label in Profound Formations was an exaggeration. Although the content within was elementary level, it was enough to impress Mu Yu, who was a beginner on the subject. He learnt how some smart humans used the stars' alignments to set formations, setting the course for the discipline's history. Cultivators eventually substituted for stars to cast formations during the war against the elemental demons.

Ku Mu expanded on Eight Trigrams Formation. He even created an Eight Trigrams Formation using fiend beasts to drive home what the eight positions represented. When Mu Yu entered the formation, the Body Severing Realm wyrm almost had him for dinner. Henceforward, he lost interest in the formation.

Though Mu Yu was keener on studying formations compared to poisons since he had witnessed many and been the victim of them, Ku Mu wanted Mu Yu to invest more time in Poison Scripture. If Mu Yu combined his special ability with the knowledge from Poison Scripture, he would have an easier time searching for nine qi soul purifying flowers and dark herbs. As part of the curriculum, Mu Yu also had to experiment with mixing herbs in addition to reluctantly memorising herbs. It was ironic for him to struggle as his special ability was directly related to plants.

Noticing there were unnecessary additions to Mu Yu's "hundred poison eraser", Ku Mu stuttered, "Th-th-th-"

"I am aware it is not correct. I was purely curious what I would produce," interjected Mu Yu, nonchalant.

Boom!Mu Yu's curiosity was sated. The resulting explosion smothered his face in ashes, and half of his face was comically swollen. He frantically used his old trick, passing the poison to the celestial fiend tree. Not even Ku Mu could resist the urge to grin. For once, Mu Yu didn't perceive Ku Mu as annoying when he saw the latter's smile.

"I-I-I-"

"You envy my ability to control trees, yeah?" Mu Yu speculated Ku Mu knew about his unique ability considering Ku Mu knew so much about Feng Haochen already.

Having cohabitated for several months, Mu Yu got a pulse on Ku Mu's temperament. The elder wasn't a man of malice by any measure. People kept him at arm's length mainly due to his research on poison and stuttering. Through knowing the elder better, Mu Yu's ability to finish the elder's sentences improved.

Besides passing on knowledge, Ku Mu also used Mu Yu as a lab rat because the latter could get rid of any poison. In the past, Ku Mu had to capture fiend beasts to test his concoctions, but Mu Yu's ability reduced the workload significantly.

"C-c-come try th-this vial…"

"Again?"

"Last. Time."

"You said the same thing two days ago!"

"C-celestial fiend fruit's function?" asked Ku Mu, lifting the corner of his lips.

"Fine, fine."

The moment the stomach-sickening yellow liquid hit Mu Yu's throat, he coughed due to the burning sensation. His heart rate dropped. Energy seeped out from his body. Normally, he could force out the poison using his spiritual energy. Howbeit, Ku Mu managed to seal Mu Yu's spiritual energy.

"How does. It feel?"

"I feel. Nauseous. I want. To gag. I'm tired. I want. To die…" stammered Mu Yu, tongue hanging out as he desperately tried to draw air in.

"Here, drink this." Ku Mu passed Mu Yu a vial of red liquid.

The mixture of sensations slowly faded once Mu Yu drank the red liquid. Once homeostasis was restored, Ku Mu nodded. "Plague. Spread. Works."

"Gramps, what do you need a plague poison for? Are you planning to kill some people?" exclaimed Mu Yu, afraid he was abetting to a murder.

"Am. I. So. Sinister?"

"Are you not? How many people have you killed in Ku Mu Valley?"

"Their fault. For lacking. The survival. Attributes…"

"Your nemesis is my shifu!" Mu Yu tried using provocation to smooth out Ku Mu's speech for his own sake.

"That son of a… Is it my fault they ventured into a valley they weren't qualified to? Stupidity begets consequences. Had you not entered and managed to pass my test, I couldn't care less if you were a skeleton already."

Ku Mu explained the entire test was to find someone worthy of inheriting his knowledge to search for a dark herb. In regards to why he didn't go pluck the herb himself, it was a mystery still.

"Do you leave the valley every now and then with your new products to experiment on living people?"

"Bingo."

"I am not testing poisons for you again!"

"Haha. Haha. How does. It feel. To be angered? Now you. Know how. I feel."

Mu Yu jerked his head back, eyes wide.

Ku Mu followed up with another question. "Want to. Join me. On a. Trip outside?"