I like the artstyle and music. Combat system is nice too, BUT I think game could much-much better and easier, if you roll in the direction which your character is facing, not where your mouse is. Otherwise I often rolled in the direction to the boss, but since I stayed a bit away from it, I was getting rolled in the boss's sprite and was getting contact damage. So this kinda encourage you to not fight the boss during its attack phase, cuz it is a bit tricky to attack and roll in the right direction. But if you could attack in one direction and roll in another, that's add more dynamic, because it actually becomes easier to attack the boss during its attacks.
Also yeah, 2 times had a bug where your character cant move and do anything and it also becames invulnerable https://ibb.co/G4wf6Hrs. Before that happen, your character gets pulled a bit to a certain place. I think it is somehow connected to the roll.
Also at first I missed that you need to hit a bell to start boss rush, so perhaps could make it more distinct or could just make so you can activate it with "E".