I Made Up Forbidden Spells, and They Actually Worked? - Chapter 83 - : The Bloodcloaks and Another Magic Lesson

After being reborn in a sci-fi ABO world, Xi Wei became the newly born son of the Imperial King. He thought, as the emperor’s son he could live a carefree and imposing life, but unexpectedly the First Prince is actually an omega? What the hell is an Omega?

There was an alpha who was born on the same day as the First Prince Xi Wei, the two children grew up together. When Xi Wei looked at the blonde child next door, he always felt that the boy was not pleasing to the eye, so as a child Xi Wei bullied him.

Until many years later …

Looking at the man standing in front of him who was one head taller than him, Xi Wei was dumbfounded.

–He tried to get out of the way, but eventually still fell into his childhood sweetheart’s clutches.

- Description from Novelupdates

Reborn in 2004, facing the age where pigs can be blown up, Lin Xuan, carrying the “Strongest Cottage King System”, started galloping…

- Description from novelbuddy

Ethan possessed everything one could desire, wealth, happiness, luxury cars, and a loving girlfriend.He had never fought a day in his life, but then suddenly, he woke up in a different world.A world were destruction and bloodshed was the norm. A world where the weak had no place to survive.Ethan now possessing the body of a boy who had failed his awakening twice and was on his last try, now stood in this world.Can Ethan who never fought a day in his life survive in a world where battles and death occurs every second, minute, hour and day.Would he rise through the ashes of the world, or would he burn with it.

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.