Mana was an energy mixed with purified Essence and the madness of Corruption. When a woman leveled up using the mana of other monsters, they also ingested that madness along with it.
It accumulated slowly and affected them. But if it ever managed to conquer the sanity of the said person, they would lose control, and the Corruption would turn them into Abyssal Creatures.
Abyssal Creatures were abominations that lived in the Primordial Expanse. Their minds were perverted, bizarre, and alien. They were also known to fight amongst themselves on occasion, but mostly only inside the Primordial Expanse.
On Earth, their single goal would be the destruction of everything in their path.
They were indeed insane and filled with madness, but that didn't mean they lacked sanity or intelligence.
Their sanity was rather perverted, sinister, and ineffable, contrasting sharply with what humans considered sane. The Abyssal Creatures had no strong sense of self.
