Ultimate Iron Man - Chapter 15: Cold calculation

Leon is an average high school student who likes to watch anime and read novels.
He's about to cross the street, only to be greeted by a truck and died.
But, he got reincarnated as Uchiha yet dead again because Itachi killed him.
Leon got reincarnated again as the grandson of the recovery girl.
He got kidnaped and tortured by All For One.
After his third death, he got reincarnated as a son of Bibi Dong.
In this fourth life, he wants to change his fate to become the strongest.

Note: Please read the tag before reading.
- English is not my first language, so there would be grammatical mistakes in this story.
- Please give my story a proper review.
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Prince Kaelen Verath is a royal disgrace—a “good-for-nothing” heir who drowns his shame in wine and brothels.But when traitors slaughter his family and reduce his kingdom to ashes, Kaelen’s desperate pact with the Voidwell, an ancient power that consumes souls, grants him unimaginable strength… and hollows him into a monster.Death offers no escape.He becomes a regressed prince who once watched his kingdom and family burn, only to fail in avenging them without losing himself.Now given a second chance, he refuses to settle for mere survival or revenge—this time, he wants everything.Every empire, every kingdom… all under his control.But with every soul he consumes and every ounce of power he gains, a piece of his humanity is lost.How will he balance power and control?Can he become a supreme ruler and still remain himself?What is the cost of Absolute Sovereignty?————Send Powerstones for a guaranteed mass release!

All it takes is one monster for the world to go to ruins.Life as Nadine knows it goes to shit and she has to accustom herself to life underground, that is until an accident forces her out into the real world.Caine has no idea why he saved Nadine.She is everything he hates- rich, spoiled and entitled- and yet, he couldn't just let her die.Living outside is hard enough without having to save someone else and yet, he does it with Nadine.Thrust into a world that she has no idea how to navigate, Nadine is forced to rely on Caine.Her life is literally in his hands.They soon realize that maybe the monsters are the least of their worries.

In a world where dungeons were an essential part of it, Rein was trying to conquer as many as possible. They were the key to gain powers in the fastest possible way. So, to reach his full potential and to become the strongest, he became a great dungeon conqueror.With his trusty friends and lovers, he was definitely going to reach the peak alongside everyone. Join Rein and see how he went from strong to stronger and then the strongest.__________________1. The harem would not be too large(I'm not sure how many but probably just 4-5 main and few other here and there). All the girls would be getting their time and story.2. The story is starting when the MC is in the middle of his growth stage and not at the very beginning. But his beginning will be mentioned in the story in some form.3. I don't think I need to mention this, but obviously it will not have any NTR, rape or that kind of stuff. It is actually quite a wholesome story focusing mainly on adventure, action and bit of romance and slice of life.