Just got to stage 5! That pattern where the floor 2 boss sends out lines of insects got me.
A little side note: Barrier needs a nerf. Same damage per bullet but twice the amount of bullets? Just get all possible purple notes, a few blues and yellows, and you kill any boss or mini boss in 10-15 seconds. And is synergises with almost every weapon! Scattershot, turrets, double trouble.. Please nerf it, just get less damage so that to be OP you need both barrier and heavy bullets, otherwise get get that weapon and you can easily get wherever you want, i died cause i was playing around and not being focused :/