Heaven's Greatest Professor - Chapter 31: Dungeon Core

The god king of Xiaoting in the upper realm fights down, and the spirit of the mixed dragon spirit is reincarnated on the earth, runs rampant in the city, and then fights in the sky.

Those who obey me prosper, those who oppose me perish!

- Description from novelbuddy

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!
With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!

- Description from Novelupdates

True evil needs no reason to exist.

“All living creatures must die, but I wont. ”

Once known as the most talented and knowledgeable scholar/philosopher across three continents, he basked in the praise and reverence of those around him. However, tragedy struck one fateful night when he bore witness to the cold-blooded murder of his entire family. Driven to madness, he embarked upon the path of power, the path of negative energy, and thus, The Great Demon, Badur, was born.

In a single day, a mountain of corpses were stacked, many of which fell to his blade. However, during his final pursuit of revenge, he met his untimely demise. His soul was extracted and cast into the void, where it would endure eternal suffering.

However, his jouney would not end here……

“What do you desire?”

A grotesque creature floating in the void asked while staring at the bruised and beaten soul of a young man.

[Ding!! Host has received Void grade Treasure]

[Ding!! Goal has been set : Attain True immortality]

A new lease at life is presented

A deal with a Demon filled with resentment

A new journey, a new Dawn

With that the great Demon, Badur is reborn

ps: the book won't progress the way other novels have been progressing. if you don't like a unique development then maybe this isn't the book for you.