XIETIAN
Theory: Bai Zemin is Sirius in the future. The Ice Goddess Skados is Shangguan Bing Xue in the future but they both reincarnated themselves for some reason and Skados split herself into two reincarnations: Bing Xue and Lilith so that Lilith can help Bai Zemin to get stronger faster for something they had to face in the future. That is why the soul resonation of both Bing Xue and Lilith is at a extremely high level with Bai Zemin. It also explains a the talent shown by Lilith, to reach 6th Order within 100 years since even though they don't have the memories, there's still probably some instinct. That dream vision of the man Bai Zemin was probably Sirius and if he Bai Zemin, then it looks like an evolved version of the Blood Berserker skill which probably activated since Bing Xue died which is why they did the drastic decision for reincarnation. Since part of the soul already dissipated, Zemin probably decided to reincarnated most of soul into Lilith to help her become stronger faster to help him which might also explain why Bing Xue is still much weaker than Zemin. Edit: More evidence that Zemin is Sirius after reading the next chapter is the use of the gravitational magic used as well as the wolf projection. Even the current Bai Zemin made an armour that is related to wolves in someway so all of these skills prove that he is Sirius. Give a like if you think it is correct or a comment if you find something to improve on or a discrepancy.