Dual Attribute Spiritual Energy was rare, even among immortals. It meant that a person's spiritual energy inherently possessed the properties and characteristics of two attributes. Such energy could only be created by a dual attribute spiritual sea. Having such a spiritual sea was a requirement to be able to cultivate more than one Dao.
Each of the myriad profound laws of nature and elements was a separate Dao. A cultivator could barely handle practicing and researching the secrets of a single Dao, let alone two. But if one was able to cultivate two different Daos, it was like they had two weapons instead of one. They would automatically have the advantage in any fight against an equal immortal with only one Dao. It was simply heaven defying!
Chen Wentian thought about his own Dao and how it was able to break certain laws of the heaven but even he was not able to utilize two elements at the same time... well technically.
Regardless, the five of them gave him a tremendous surprise and he was delighted. Their new found power meant that their path towards immortality was pretty much set. He needed to find an immortal fire art in addition to the immortal ice art he promised them. He had to work hard since he didn't want to disappoint them.
What he was curious about was how all of them obtained the power at the same time. They weren't innately born with affinity towards two attributes. Such a physique would be incredibly rare and there was no chance five unrelated girls were born with the same power. He considered all the variables including the Eternal Winter Sutra, Frozen Netherworld Jade, Blue Dragon flames, and his yang essence. Any one of them by itself would not result in dual attribute spiritual energy. He could only assume that all four blended mysteriously together and caused the women's spiritual sea to evolve.
Chen Wentian also noticed that his yang essence played a bigger part than the other three. His stuff was unique because it was constantly nurtured by his Blue Dragon flames and carried an incredibly high density of yang fire. Its quality was even higher than the ordinary Blue Dragon flames that he wielded.
He didn't know why, but the girls were able to absorb his yang essence to improve their dual attribute constitution even without the presence of netherworld yin energy or dragon flames. It didn't matter if he released during training or lovemaking, they absorbed it all the same. He could recall every single time he came inside of the girls and Li Yuechan and Song Wushuang were tied for the greatest number of times. They both happened to have slightly better fire resistance than the others, which would correlate to slightly a better dual attribute constitution.
He was still confused and he decided that one more test was needed...
The girls needed a couple days to fully recover from the cultivation training and they could not exert their spiritual energy or practice martial arts during that time. Chen Wentian explained to them the second form of training for them to improve their dual attribute constitution. They didn't seem too keen about it at first, especially Xu Lanyi, because in their eyes it was simply sex.
He patiently coaxed them and explained the potential of having two immortal Daos and they all eventually agreed. Thus, six willing hearts joined together and the Plum Blossom Villa was taken over by endless cries of pleasure for two days and two nights.
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Li Yuechan and her sisters recovered their spiritual energy on the third day and Chen Wentian took them down the mountain. Apart from the initial cultivation improvement through the netherworld yin energy, they didn't experience any other increase in cultivation. They were eager to see what improvements they gained with their dual attribute ability and to make sure they had not suffered through a two day orgy for nothing.
"Alright! Let's test elemental resistance first." Chen Wentian said as they gathered in the courtyard of the sect. "Your dual-attribute spiritual energy contains both ice and fire. The ice portion of your spiritual energy cancels out a portion of the fire spiritual energy from any attack. The remaining portion is then consumed by the fire attribute of your energy. This is how your spiritual energy is able to deflect the flame attacks from the Blazing Sun Art. Let's try it out again. Yuechan, you first."
Li Yuechan walked to the center of the courtyard and he repeated the previous experiment with her once again. Her cultivation had improved by a decent amount but it was still at the upper realms of the 6th Level of the Spirit Initiate Realm. He threw a large number of fireballs at her which she all deflected.
"Okay, good. Wushuang, you're up." Chen Wentian said.
He quickly tested all five and found that there was a small but still detectable increase to their ordinary fire resistance. It was exactly what he wanted. As long as their dual-attribute constitution could steadily increase, it meant a world of possibilities.
"I want to test out your ice attribute. Yuechan, can you try out your Eternal Winter Sutra to see if there is any change?" He asked.
"Yes."
Chen Wentian watched as Li Yuechan formed a familiar ice sword within her hands. Crystals of clear ice erupted from her palm and slowly grew to a meter in length. It was still very slow but a bit better than before.
"Give it a try."
Li Yuechan obliged and swung her newly created ice sword. It whistled and glowed and left sparkling flecks of ice in its wake where the air had been frozen. The ice sword was still solid, a huge improvement from the first time. She swung it again but this time the ice sword had already started to disintegrate and was gone by the end.
The others tried as well with about the same result. Their control over ice energy had improved greatly but the compatibility with the Eternal Winter Sutra was still bad.
"Don't worry, dual attribute is much, much better. Your ice and fire resistance will improve over time. Even if you get into a fight with Glacier Palace, you'll still be fine." Chen Wentian explained, "I promised to find suitable ice art for you and that is still a promise. But now, I will also find a fire art for you as well."
He chuckled as their glum faces turned into happiness. "For now, what you need to do is to increase your awareness and control over your dual attribute spiritual energy. You can go back to Red Bamboo Province and continue to train. When you're there, focus on sensing the two elements that are hidden within you. While it may feel normal it actually contains both ice and fire. But you have to be conscious of this at all times, understand?"
"Yes, master!"