Fortune Teller Master - Chapter 119.2: Jagger Part 2

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

Daytime belongs to the human world, while Deceit Night returns to the netherworld.Since the arrival of the sinister night, demons and evil spirits have brought disaster to humanity, and generations of our ancestors have struggled to survive.This blade of mine can eliminate evil, slay demons, defeat wickedness, exterminate devils, destroy evil!From now on, nighttime shall be like daytime!

“I want to be someone who matters. And I want to know what it feels like to be in love.”Ezra sold his soul to the Storyteller for a chance to live in a world of magic. But Oberyn? - he was cast away from his home, shackled by a destiny he refuses to obey.But destiny isn’t the only force pulling their world apart. A surge of wild magic threatens to unravel everything, and neither can control it. If they want to survive, they’ll have to surrender to something even more dangerous: each other.At first, they’re reluctant allies. Then friends. Then… something neither of them is ready to name.Ezra is plucky, affectionate, and full of heart. Oberyn is proud, aloof, and single-minded in his goals. They couldn’t be more different - until Ezra’s Desire System reveals the one thing Oberyn wants more than anything else.In a world where magic bends to will, control is everything. But when fate ties them together, who will be the first to give in?Genres: Transmigration, System, Magic, Romance, (R-18), boyxboy (bxb)

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.