Great game with much much potential, playing with some silly tropes and creating a good immersion into the world's magic system. At first i had a serious problem with the girl's fighting system, since it gives no tutorial or example how to use it properly, but with a bit of persistance, i understood the geniality behind it, making every move seem critical, without anyone to hold your hand, you evolve and adapt and find the best strategy to your goal. My personal reccomendations would be the following:

1- If possible, make a way to get more money in game. Some upgrades are too expensive, especially the ones critical for rune exploring. The ability to restat everything at zero cost was really helpful, but eventually the only way to progress was to fight all the girls again to have enough money to buy a single health upgrade. Also, different ways to make money could expand the game's universe quite a bit without much need to create an elaborate system. Just use the creativity you've had so far and i'm sure you'll fare well.

2- Add more girls. This one is a given, we want more cuties and it would add variety to both the fighting system and the prisoner system. No actual need to develop them so much, we can set some primary and secondary characters, in a way that the secondary only have one or two sex scenes, to be easier to implement. Additionally, have the amount of prisoners you have influence your power in battle could be useful to overcome the money grinding problem i faced, but i thik you already are in your way to implement that with the idea given by Donna, but since we cant develop too much of the characters relationship for now, i guess it will remain impossible for now. 

3- PLEASE POST MORE UPDATES!!! I've played almost through all the content in a single day, and that's because i'm a story completionist that wanted to see every single possible reaction on the h-scenes, and that took some time. It's been over a year since your last update at all, and even more since your update to the game itself. Please, come back to posting more and allowing people without enough money to properly support creators to enjoy and maybe give a bit of insight to the developing of your games.

To finish it off, a small scattering of tiny bugs i found and some less important suggestions: none of the bondage scenes show the amount of cum accumulating inside the girls. during the fight, using x-move to lick targeting their waist ends up consuming no mana at all. Sometimes, cumming during A-sex shows up the womb filling up, like it was regular V-sex. And a tiny suggestion since i'm a A-sex lover: Please, make xray for A-sex as well.