> Unless you manage to reach like 20 times more than what a human's natural limits would be, good luck beating her. So, assuming a coomer managed to actually do this, he could overpower her spell and turn her into an obedient wife against her will.

Funny, this is precisely the premise of a doujin

Pretty much.

Aura, the demon girl (mom here) is a ruthless killing machine. All demons are like this in this world, they are basically human mimics with no redeeming quality, very black and white.

She uses a powerful forgotten spell that pits her magic power against another person's. Whoever has more gains (almost) complete obedience over the other. Of course, she has a monstruous mana pool, so unless you manage to reach like 20 times more than what a human's natural limits would be, good luck beating her.

So, assuming a coomer managed to actually do this, he could overpower her spell and turn her into an obedient wife against her will. Leading to children who, if they are even possible, are very likely to be psychopathic killing machines like the other demons. That is not even talking about the fact that the spell is not perfect, has loopholes and can be broken temporarily with iron will.

For short, you may use magic to stick your dick in crazy. But you will lose said dick and a lot more way before you can reach this point.