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This idea is that someone from our world is reborn into the world of TBATE as Cadis Etrama Di Raizel without the weakness of life force consumption every time he use his powers.
For Backstory
He comes from a noble family from the human kingdom. There family bloodline gives them the power to use blood magic and sometimes other abilities nobles from noblesse have. The mc will be the most powerful person of his bloodline and have all the abilities of Cadis Etrama Di Raizel and look like him.