Title: As an immortal, I only learn forbidden skills. Tldr, lost it's plot midway.
I tried reading this novel, and it was... Readable up to midpoint. Around ch 600 or even earlier, it became visible that the author of the Novel forgot the reason behind the title.
Now, I might be hasty, as I am dropping this novel due to the reason, but it is hard to read a novel that started with the very real idea that the main character is immortal. Doesn't age, and can heal from every possible wound. Essentially, he can't die. But at some point the author simply forgot that this is MCs power, and MC started worrying "Omg, I might die because of this XYZ thing" and so on.
I can only say, the idea was decent, the execution, after some time, not so much.
Personally, I'd want to give it a ... Grading... But given that I was able to read only half of it. It does not seem fair.
In case someone else has finished it, do give a reply as to whether it's worth keeping reading it.