The way the technique with a long name worked was it took advantage of the fact that during dawn and dusk the qi that the sun generated was much 'gentler' and could be absorbed with mostly no problem. This was due to a small amount of the moons qi lingering around during the dawn and starting to form during the dusk.
That moon qi would clash with the sun's qi and weaken it to an extent, the user would then breath in deeply while also pulling in the surounding qi to draw in the 'purple sun qi', which was just a mix of sun and moon qi. It was made to mimic the growth cycle of a golden crow, which would live in areas full of sun qi breathing it in as they grew.
The reason why the technique didn't just absorbe sun qi or moon qi was because sun qi was increadably hot, as it had a very high level of yang energy which contained the concept of 'heat', making it such a high temperature that if a normal person tried to absorbe pure sun qi, they wouldn't even have ashs remaining to bury. It was to opposite for moon qi, it would turn someone into pure ice before they could every try to process it. So the only moment where someone could reasonably draw in sun qi was when it had mixed with moon qi, cooling it down enough to use.
The reason moon qi wasen't used was because it had the stigmata of being 'deminic' because it was yin, which was just stupid. It was the same as saying a piece of ice was evil because it was cold. Demons and 'evil' spirits used yin energy because yang had the trait of purification, which was acid for most of them. That wasen't to say there where all demons or spirits only used yin energy, if they managed to find a work around for the purification then most would use it because it was 'more energetic' and had the trait of vitality, which could help them progress at a rapid pace.
Back on topic, Alex planed to use purple sun qi, and the moon equivalent of red moon qi, as a mediator for the pure sun and moon qi, he would absorbe purple sun qi and red moon qi during dawn and dusk, and then use that as a 'cushion' for the sun and moon qi during the day and night, limiting the effect of its heat and cold.
Of course, he wouldn't jump strait to pure sun and moon qi. he was going to copy the first step from spirit cultivations body forging, he would draw in a very low purity piece of sun and moon qi, alow his body to adjust, then draw in a more pure piece, rinse and repeat. Once he had absorbed a piece of pure sun and moon qi, after he had advanced to qi absorbing, he would use each as a focal point to draw in more, forming a small 'sun' and 'moon' around his mind palace, with the mind palace itself being built out of purple sun qi and red moon qi, along with more energies in the future if he felt like it.
With his plan in mind he got to remaking the technique. Firstly get rid of the breathing, that was stupid and only acted as a activation for the rest of the technique. Second, make it passive, automation was king. Third, make it so the cloud of energy wouldn't form around him, he was going to use his new fancy furnace to make four new energy cryistals which would store each of the qi's he was going to absorbe. Fourth, change thay God damn name. And finnaly fifth, start.
Over the course of a week Alex ended up having to compelatly rework the technique as the changes he wanted to make where near completely incompatible with the existing technique. He ended up with the finished product which he called the [twin phoenix soul scripture]. In the process of development it had evolved into a low sky grade technique, which added with the heaven grade modifier, it now counted as a (low celestial grade) which apparently what was after heaven grade.
"Alright, let's try this out." Sitting down to start Alex activated the technique, it was curently dusk, as he planed to absorbe red moon qi to balance out the purple sun qi. A steady stream of red qi began to pool around him, forming a thick mist, then clouds. But was quickly absorbed by the energy crystal made for it before being drawn into his mind palace to form more bricks.
Once the moon had completely risen Alex braced himself as a biting cold began to flood his entire body, he felt like his blood had frozen over. a thin white mist formed around him, That mist wasen't moon qi, it was the water condensating around him from how cold his body had become.
A thin sheet of ice began to form around him as more moon qi was absorbed by him, and this was only 0.1% pure moon qi. But his body began to steadily adapt to the cold, despite the fact that the purity climbed to 0.2% he stayed the same temperature, the climb to 0.3% was faster, then 0.4% fatser still. In an hour he had climed to 1% pure moon qi while at a steady temperature. In the second hour he was at 2.5%, the third 6%, the fourth 20%, at five hours since moon rise he was absorbing 50% pure moon qi. 6 hours in it was 75%, 7 hours 90%, 8 hours 99%, and just before the sun rise Alex absorbed 99.999% pure moon qi. Stopping there on purpose as if he absorbed 100% pure moon qi he would advance to the qi absorbing stage ahead of schedule. As the sun rose he began to absoreb the purple sun qi, which he had started at 99.999% pure a week ago.
This time he braced to absorbe the sun qi, and as the sun fully passed fhe horizon Alex went from feeling like his blood had frozen over to feeling like his blood had turned to magma, steam rising around him as the frost suronding him melted and the wooden floor under him began to char black from the heat.
After another 10 hours Alex had absorbed 99.999% pure sun qi, his body fully adapted to both.
[Congratulations host for naturally gaining the trait [sun and moon body: tier 2] by absorbing near perfectly pure sun and moon qi.]
[Sun and moon body. This physique is the result of the host being able to absorbe both sun and moon qi, and survive. Grants a high affinity to yin and yang, alows the host to absorbe sun and moon qi with minimal consequence, elemental affinity raised greatly, resistance to heat and cold raised greatly, enlightenment slightly less rare.]
"Oh damn. That's nice."
Due to people reading my novel, having a mass release. its on the house