Okay… start with a barely alive MC, put him with an OP Core that takes a long time to unlock. Then have bad guys come in to hurt him more. That part is pretty good, and the new core, see the book title, is interesting.
But then… the character is in his own head A LOT. One chapter, he eats a mana mushroom. It’s the best thing he’s ever had in his entire life. It’s the best thing he’s ever had in his entire life. It’s the best thing he’s ever had in his entire life. Expand to fifteen minutes. This is a 26 hour book that could have been trimmed to 13 hours.
“Hey, want an apple?” A different character sees the MC brooding in his own mind for 10 minutes straight and offers an apple. I had to laugh. When the story has dialog, it’s okay. The fights are well done. Often, though, the character starts a headspace moment and I know what the next ten minutes will be.
The progression is good. If you like stories with extensive internal dialog, you’ll like this one. I would have preferred trimming.