Really fun!
Though I do think it's missing...something? The combats go on forever, and I haven't found too much build variety (but it is just a demo, so whatever)
Maybe also have the player heal 20 hp after each boss? It feels kind of bad to have all damage be effectively permanent.
Yeah of course :)
Oh, one last thing, that I think would really help the balance of the game:
Currently, the Soul economy of the game feels really stifling. Then, once you find Soul Core (+1 soul per enemy killed), your Soul economy practically doubles. It makes Soul Core feel like practically a necessity for any good run.
Could you have the base rate of Souls gained per fight like 50% larger, while making the Soul Core give ~50% less souls?
With this change, the Soul economy would feel a lot less brutal, while also making the Soul Core feel less critical.