The Immortal of Plague begins by establishing the root of lung fire.

Thirty-odd copper coins were scattered on the rough bedding, their surfaces covered with years of dirt. Song You gathered the coins into a pile and pushed them under his pillow.

His attention was not on these gold and silver things at all; in the Taoist temple where human life was as worthless as grass, worldly currency did not play a significant role.

The Lung Fire Technique manual distributed by the outer elder was placed beside him; it was the only path to survival that Po Cang Temple had planned for these surviving immortal seedlings.

But Song You had another option: the nameless booklet he had taken from Jiang Yangjiao's corpse was quietly pasted in the lining of his pocket. Before that, he needed to compare the merits of the two cultivation techniques.

He opened the book "Lung Fire Technique" with its dark red cover. The paper was rough, and the ink was slightly smudged at the edges. The first few lines explained the foundation of this technique.

The lung fire channel root has the inherent characteristic of spreading diseases, but this can be controlled by humans.

To practice this method, one must use the heat source in the chest cavity as a guide to ignite one's own lung energy within three days of planting the root of lung fire.

Once this step is achieved, the entire lung will gradually fuse together, radiating an invisible flame that the book refers to as the outer flame.

Once the outer flame is lit, one has officially entered the first stage of cultivation: the firewood stage.

The book records that after entering the firewood stage, the daily practice is to use this fire to burn the lung qi. Over the years, the entire lung will be transformed into a furnace, thereby breaking through the shackles of the human body and entering the next realm.

Song You closed the book, his fingers repeatedly stroking the rough cover.

This cultivation logic completely overturned the physiological common sense of my previous life.

The lungs of a normal person are organs for gas exchange, and their internal structure consists of countless tiny alveoli and a dense network of capillaries. When the temperature exceeds a critical value, proteins denature and cell membranes rupture.

This is clinically known as thermal injury, usually accompanied by severe tissue necrosis and edema. However, the method of the Po Zang Guan (魄藏观) aims to transform this delicate organ into a continuously burning furnace.

From a medical perspective, this is essentially a controlled form of chronic self-immolation.

However, this is now another world. People in this world will not die because of this. The cultivators' bodies have undergone some kind of mutation, enabling them to maintain the functioning of life under such extreme high temperatures.

This process of mutation is inevitably accompanied by unbearable pain, which explains why those cultivators are all emaciated; their physical structure has been completely transformed by this morbid cultivation method.

It is worth noting that the practice places special emphasis on the decisive role of the quality of one's Dao root.

The heat source planted by Elder Zhongzao, also known as the Dao Root, is called the Inner Flame in the cultivation technique.

No matter how hard one tries in subsequent cultivation, one can only strengthen the outer flame, while the size and intensity of the inner flame are already fixed the moment the furnace is planted, and there is no room for change.

The larger the inner flame, the more intensely the outer flame burns, the faster the cultivation speed, and the greater the probability of breaking through to a higher realm.

This explains why the outer elder looked down on Shen Lu, and why the boy who was taken away alone was valued.

Shen Lu's inner flame, no bigger than a fingernail, provided negligible heat; it would take an extremely long time to accumulate lung energy to ignite her entire lungs. The boy's inner flame, on the other hand, was likely far larger than normal, giving him a significant head start over the others.

He looked down at himself; the fist-sized inner flame in his chest was pulsating rhythmically, radiating a continuous warmth—a mediocre aptitude. However, on the path of cultivation, this was far too meager.

However, I do indeed have an incredible opportunity.

He stood up, walked to the door, and peered out through the crack.

The night was deep, and the outer courtyard was quiet except for the rustling of the wind through the withered bamboo grove. From Shen Lu's room next door came a few faint, suppressed coughs, accompanied by the creaking of the bed.

He walked back to the bedside and took out the small booklet wrapped in oil paper from his inner pocket.

Unwrapping the oil paper reveals a blank booklet with the four characters "養气化神" (refining qi into spirit) neatly and rigorously displayed on the first page.

Continue turning the pages and reading word by word.

This booklet takes a completely different approach. It lacks the self-destructive cultivation methods and morbid internal energy. Its core lies in sensing a certain energy that roams freely between heaven and earth, which the book refers to as spiritual energy.

Through specific breathing techniques and meditation, spiritual energy is drawn into the body, flowing along specific meridians and ultimately converging in the dantian in the lower abdomen to complete the energy refinement. After the energy refinement is complete, the foundation building process begins.

This system is peaceful and progressive, but it relies heavily on the practitioner's own aptitude, that is, their affinity for spiritual energy.

It does not require destroying the original physiological structure, but rather strengthens the body through external spiritual energy. Compared to the violence of the Lung Fire Technique, this method is more in line with the logic of biological evolution. It emphasizes the unity of heaven and man, rather than the plundering and alienation of the Soul Treasury Technique.

This statement aligns with his understanding of the true Dharma.

Song You placed the two books side by side on the bed.

On the left is "Lung Fire Qigong," an extreme path that uses one's own lesions as fuel; on the right is "Refining Qi and Transforming Spirit," a legitimate yet unknown path.

He began to weigh the pros and cons.

The Lung Fire Technique is a traditional method passed down within the Soul Treasury Temple. Although cruel, it has a complete system and is supervised by an outer elder. Most importantly, the Lung Fire Dao Root has already been planted in his body. If this inner flame is not guided, it will completely spiral out of control in three days, burning his internal organs to ashes.

The book "Refining Qi into Spirit" has no lineage or predecessors to guide it. Whether the contents of the book are complete or have been deleted or modified is all unknown.

If he experiences reversed meridian flow or qi deviation during cultivation, he won't even have anyone to ask for guidance.

Importantly, if he chooses to cultivate "Refining Qi into Spirit", three days later, when the outer elder comes to check on him, he will not find a cultivator with lung fire, but will find a cultivator whose dantian is filled with orthodox spiritual energy.

Just imagining the scene is enough to foresee the outcome. A strange sect like Po Cang Guan would never tolerate an outsider practicing orthodox methods living under its nose.

He will most likely be treated as a heretic and disposed of, or become fresh food for the elders of the planting stove.

Moreover, the Qi Refining Method doesn't mention how to suppress or resolve the lesions in the body. Even if he successfully refines his Qi, he can't stop the erosion of the lung fire root; when the time comes, he'll still face certain death.

The pressure to survive is looming ahead.

He rewrapped the "Refining Qi and Transforming Spirit" book in oiled paper and stuffed it back into his pocket.

Practice the "Lung Fire Exercise" to save your life. This is the only option.

However, the method for sensing spiritual energy recorded in that booklet is worth trying.

The method for testing aptitude is not complicated. It only requires adjusting your breathing and clearing your mind to capture the most subtle energy fluctuations in your surroundings. This doesn't take much time and won't leave any substantial traces.

It also allows you to test your own qualifications.