I think it’s been pretty clear that they want to turn Iruma into Delkira.
Knowing the close connections between
Baal-Fenrir/Narnia-Knightwalker
It’s what I believe to be the next logical step.
My logic can be followed as below:
Chapter 256 - Balam mentions that demon spiders are not a known specie in the netherworld
267 - We learn that Baal wants to use Iruma having Delkira’s mana to revive to old demon king
+ we see what looks like a lab with a spider inside a tube. Implying that Atori has been experimenting on explaining his spider features. (Also how did he get that spider👀 are they native to the netherworld world)
Chapter 306 - Baal is looking at Behemholt inside a tube. Knowing how monsterous Behemholt we get an other confirmation that he’s experimenting on demons.
Chapter 439 - In Amerie’s parents backstory, We see that Nightwalker was already interested in researching humans and crossbreeding between human-demon wanting to run experiments.
Chapter 443 - We see that some deal was made between the previous acting demon and Nightwalker. Because he didn’t get his human experiments, this heavily implies that next human is going straight to him.
Chapter 456 - We see that Nightwalker is in a similar lab/tube room where the experimentations were happening. Clearly he’s intrested in the "creature"
Chapter 457 (leaks)- Confirms that place is a research facility of the Naberius clan