Talk:Incubus/@comment-27950421-20181102125449/@comment-10429980-20181102230356

Another thing to keep in mind though, is that once your mana amount reaches past a certain point the growth slows down immensely (KC mentioned this when explaining why after a thousand years of growth since defeating the chief god, the mamono lord still isn't strong enough to enable incubi to be born). Hence why non-undead incubi with harems aren't immortal, their mana growth slows enough that their life span catches up.

Even those with perhaps the most immense individual mana we know of in the setting, like the mamono lord, have a limit to their lives, KC once having stated it may be around ten thousand years.

Undead of the current era on the other hand live forever (as far as we know) not due to the immensity of their mana but due to them being a different type of life form whose soul has basically been bound to the physical world and thus regardless of the state of the body the connection with their soul remains and the body can be repaired.