Thank you so much for your comment! Sorry for the late reply, but I've been quite busy lately...
I really appreciate your feedback on the current balance. Honestly, those are things I struggle with quite a bit, because as a developer, I don't really notice if the balance is right until a third party tests it. So, I truly thank you from the bottom of my heart for your critique on that section.
Regarding the exponential damage upgrades, I’d like to keep them scaling that way, but I will most likely nerf them even more so they don't scale so aggressively. As for the regeneration, I will also increase the time it takes to heal.
Regarding the Repulsion Burst, for now, I'll leave it as it is with the automatic activation, but I might change its description to make this clearer and tweak it a bit. If I see it still doesn't feel right, then I'll switch it back to activating only when it detects an enemy.
Finally, I'm aware that once you get completely surrounded by enemies, there isn't much you can do other than just "accept your fate." I'll look into a way to change this so players also have some room to make a decision.
Again, thank you so much for your comment! They are definitely super useful!