I have somewhat mixed feelings about this novel. This novel had a great idea, and for the most part the plot was pretty good. However a few things didn't make much sense.
So first off, the main character. He has lived in the void for trillions of years. It was stated his lost his sanity and regained his sanity multiple times. Putting aside the fact that humans trapped in a void for trillions of years would likely never regain their sanity, when he gets out of the void is where the problems start. When the main character eventually is reincarnated as a human, despite what was mentioned previously he still has quite a bit of emotions. He is not really a "cold calculating" as initially described, he is empathetic but kills to get to his goals. The problem with this, he has literally lived in the void for a indeterminate amount of eons, and has zero emotional defects? I'm at chapter 72, and he quite frankly has perfect sanity, with no emotional defects. Which, again, makes no sense.
As for the side characters? We have antagonist #1 - 10, and useless girl who stays by the main character's side #1 and #2. He keeps a annoying energy parasite next to him for no good reason, despite it endangering him quite a bit.
Also, as much as I love unforgiving worlds where the main character barely survives, this just isn't it. Literally everyone the main character meets trys to kill him at some point, it's kinda exhausting to read. I swear theres large swaths of people who will try and kill him just for the giggles.
The plot in general kinda sucks. The main character wants to learn how to use mana more efficiently, so instead of taking the short way to go to the mages association to learn, he takes the long way. (He could've revealed he has a mana core to be taken there straight away, but instead he didn't and now has to walk 5000 miles across various places with next to 0% survival rate.) Why did he do this? Because it might give too much attention to him. Which I personally find laughable, considering how much attention he has gotten so far, I doubt revealing a mana core will change anything.
Furthermore, the writing quality is sub-par, even for this site. Theres a lot of run-on sentences and a ridiculous amount of grammatical errors. Grammarly could've fixed the majority of mistakes. The conversations the main character has are kind of awkward, I can't really anyone actually saying this without being extremely cringy.
Overall, a good idea, and it had a good plot outline, but failed the execution miserably. Writing quality, story development, and character design fall short. World background is only average.