Blood Shaper - Chapter 31Book 4:

Jerry traversed across worlds and arrived in a Beast Summoning era. In this world, everyone could summon their own pets. Darkness was looming, and the world was in turmoil. Relying on the power of their summons, many shrines plundered the resources at every corner of the world like tyrants. But when everyone else was summoning adorable pets that could help them in battle, Jerry discovered that his summoned pets were a little different. Other people's pets are all kinds of beasts, but Jerry summoned gods from Greek mythology! King of the Gods, Zeus, “Master! I, Zeus, is at your command!” Athena, “I will fulfil all your requests, master!” Poseidon, “I will conquer this sea in the name of the master!” In constant summons, step after step, Jerry became the supreme ruler of this world!

Mortimer Zhu is an extremely unfortunate high school student who accidentally enrolls into an academy of a dubious nature, where it is the norm to jump in front of moving trains, get dismembered during orientation, and crushed by vindictive bouncing classrooms. Can he stay alive or will he die from the rigors of school? Why have evil spirits suddenly acquired a taste for his flesh?

- Description from Novelupdates

In the rebirth, in order to prevent the tragedy of the previous life from happening, Bai Yu decided to rush to the [Tower of God] at any cost, and face everything together with his sister!

However, Bai Yu, who was bound by the system, mutated his bloodline, and transformed into a black-scaled python seems to be developing on a completely different path from his previous life…

- Description from novelbuddy