People have the misconception that because trees are stationary and slow, they are peaceful and gentle. People would also like to believe that carnivores are the most violent beings in the world. But the truth is that carnivores are the least violent beings in the world.
The most violent beings are herbivores and plants. Without carnivores, herbivores will massacre most of the plant life in a region. This and the fact that carnivores don't eat plants make plants like them.
Plants are also violent because every moment of their lives, they are always struggling for survival and spent fighting one thing or another for resources. If they fall behind in the struggle, they will die.
The worst part of their existence is that they can hardly defend themselves against herbivores. They can only stand there and let themselves be eaten.
So Arthur wasn't surprised that the tree had so much to say about violence and killing things. He tuned out all the talk of violence and made his request.
He asked for life energy. Because he had an affinity with plants, the tree decided to give him some life energy.
The energy capacity of the wood vessel sigil technique is only 1% of the energy capacity of his golden core, so he could absorb 10,240 units of energy.
This amount is ten times the amount of energy that a cultivator at the peak of the second mortal coil possesses and a hundred times the amount of energy that someone at the peak of the first mortal coil possesses. But to a giant tree that is at the fourth mortal coil in terms of material durability, what he was asking for is insignificant.
Even a tree at rank 2 will be able to give him enough life energy to fill up his wood vessel sigil without dying. So the giant tree was perfectly fine after giving up 10,240 units of life energy.
But so that he would be able to receive more life energy from it in the future, Arthur decided to give the giant tree some life essence. He got the life essence from refining the bodies of animals and plants. So it is similar to life energy.
The main difference between life essence and life energy is that one of them is a substance, while the other is energy. Life essence is a liquid, so it is a form of matter. This makes it impure compared to life energy. And even though it is easy to digest, it is not as easy to absorb as life energy is.
But what Arthur would call impurity in life essence is a benefit to trees because they need other types of nutrients, other than life energy, to survive and grow. Life essence contains everything they need, so it is a good tonic for trees.
Once he gave the tree the life essence, it began thanking him profusely. Then it began asking for more.
It said slowly, "Give more. Give more. Give more."
The tree was incessant about getting more life essence, even though it didn't show in the way it spoke. However, Arthur had given it all that he wanted to. So he left the tree.
He left the forest and returned to his floating island. Along the way, he felt the new, powerful energy he had come to possess.
As the green mark of a leaf on his head glowed, he said, "With this, I will be able to save my life from any injury as long as my soul and core remain."
The life energy he just acquired can be used for three main things. The first use is that it can be used to shorten the growth time of plants and help them grow quickly. So with enough life energy, he can help a plant that requires a hundred years to mature to mature in less than one hour and bear fruit.
The second use for life energy is to help plants advance and break through their limits. This is what the golden core elder who helped him create a rank 3 silver pine tree did. The silver pine tree was stuck at rank 2, but the golden core elder was able to brute force its advancement by investing a lot of life energy into it.
The third, and perhaps the most important, usage of life energy for him is healing. With enough life energy, he will be able to maintain his best physical condition right until his lifespan runs out and he dies. So he will always look young.
In a war, the third use will be the most important for him. But the other two uses are no less valuable than being able to use life energy for healing.
There is also a fourth usage of life energy, which is to grow the power of the golden core and cultivate it quickly. Unfortunately, he can't use life energy for this because it will cause an imbalance in his core.
This imbalance will be caused by the presence of lightning in his golden core. So this will be the first time that possessing the two elements is stopping him from doing something that a single element can do.
Maybe if heavenly lightning could be used to cultivate too, he could find a way to grow both the wood element and lightning element in his core at the same pace and maintain the balance. Unfortunately, this isn't possible because heavenly lightning is too powerful and dangerous to cultivate with.
He could only shrug and say, "I guess it is what it is. The sole cultivators of wood get to cultivate quickly, have a longer lifespan, look young forever, heal themselves, and help plants grow, while the sole cultivators of lightning get devastating power to fight across realms. It is already a good thing that I get to have most of the best of both worlds."
He is already cultivating quickly, so he doesn't mind that he can't use life energy to cultivate quickly. Besides, using life energy to cultivate quickly is not free either. After all, the life energy has to come from somewhere.