Primordial_Space
what's the timeline? and just suggest for his spirit, set it as Shadow Devil [demon beast in TODG], it's suitable for him since he's an assassin. or same as Xie Xie's spirit, Light Dragon Dagger and Shadow Dragon Dagger. https://tales-of-demons-and-gods.fandom.com/wiki/Shadow_Devil#Manhua
I do not know if your gonna make your protagonist OP from the beginning or are gonna give him a system, but please make his charm and beauty level off the charts to be helpful to getting the ladies. In addition, try to get the MC into the Royal college, instead of Shrek to attack the ladies of that college and Liu Erlong, if you are gonna go for her and try to attack Zhu Zhuqing and Ning Rongrong, when the royal team goes to practice at soto city.