Oof yeah that's bad :D I just tried playing the game and only picking moves that gain you soul and yeah, beating the boss isn't really feasible this way since the trick is you need to keep your soul somewhat low so... this... doesn't happen.
Anyway, once the jam is done I will definitely update the boss so that it accommodates the soul gaining lifestyle! :p
Glad you liked the rest of the game anyway! Thank you for playing it until that unfortunate point!