This Is Just The Beginning

This is about a twelve year old boy in the undertale multiverse. He is born in the past during the human and monster war. When humans can use magic and he is born with the most powerful soul ever seen by man or monster. . . Even stronger than a determined one
Humans can still use magic in the present, just not as well as before.

What will he do when he is betrayed by his own kind for a ritual.