A bit neat. I beat the boss after a bit of trouble.
I think the player's range of movement is too stiff. It's what makes handling the 2nd phase awkward. But it's cool the boss has phases heh. For the first phase I just hugged against the top/bottom of him. For the second I was midscreen and threw sword. For third I circled him at a specific radius that let my sword touch but prevent his shots from hitting. I... didn't really bother with the dash button.
I think there's more that could be done but the mana system is neat and enemies giving you a refill on that is cool. Oh also the music is cool! But it also randomized itself after each game over? But all the tracks seem good.