Responses
No one can kill him he is strongest in existence
In this fight he absorb the anomaly and become even stronger but he rejects Ascension so he dies as a human since if you ascend you lose all your desire and his desire was more important for him
No he is too powerful so his physical body can't stand his power and shatters

There are too many Spoiler that some says he died some says he did not
The ending is vague
His body died that his soul became half immortal and part of the world
In chapter 629 of the novel it says he can't come to work to see the main character see he disturb the balance
It's like final farewell then his spirit disappears into golden light and the sparks fly into heaven
Some say this light means Ascension some say it means soul annihilation
In my opinion it's Ascension
Let me know your thoughts
I think it's Ascension
There are 600 side story about his and it ends with his achievement to godhood but keeping his humanity last chapter of extra is it's 20 years before start of the main novel
So I don't think this important character died.