Mutagen by Exallion

Infinite mana in the apocalypse

A novel, it's good for binge reading. But most ppl fails to see the problem with the book and says it's bad:- the main problem is the fast pace of the book. As it is the thing that makes the book exciting, but when ones catches up to the latest chapter and has to go through the grind of daily 2 chapter. The book doesn't seem that much interesting anymore and ppl calls out to the author

BUT the story also has it's MAJOR flaws:- like there is a non-existence of side character interaction and development. After a certain point even the MC himself doesn't receive anymore character development (cause he received all in the span of 500 chapters, rather then taking thousands upon thousands of chapters to get even the smallest character development like many books in WN).

Now it has ONE OF THE BEST world building (structure wise or more simply "plane of existence" wise) compared to any other WEBNOVEL.
The same is about it's power system, which can arguably be considered present ONLY in this novel(and it is only unique to this novel).
Then comes the ACTUAL PROPER OPness of the MC. Where it's not like other novels where the author just nerfs the MC only to show the inconstancy of powers and the structure of their respective story. And in IMITA the author never compromised the OPness for anything else, the MC remains OP whenever he goes and with REASONABLE explanation of power and how/why he is OP.

Now you can give it a try if you like OP MC.
Or not touch it if you like side character development, interaction, side plot etc directly unrelated to the MC

The is barely any filler in this novel(and the ones to consider it a filler are the ones who doesn't get the same lvl of dopamine they expect every single chapter)

So main judgement:the whole novel is focused on the MC, world building, power building, plots ONLY related to MC. There is hardly any plot related to side characters and stuff

Oh btw, it is harem, well.... More like just trophies he collected in every plane of existence he advanced.
And they are in no way useless baggage. They are TOTALLY useless (tho some does play a little significant role in their respective plane they are introduced. And some also plays roles in some particular instances.)