Okay, the battle was just too short. There was at least 1-2 fun mechanics from the boss and a really nice atmosphere. But this is like, man I wanted more. Expand upon the idea, there is potential. (Also this isn't really like cuphead)
(I can sequence break in the first 10 seconds and leave the stage completely. Maybe you should of play tested this and ironed it out a bit more.)
EDIT: I can sequence break TWICE within the first minute. Dude.