Unless you have an extraordinary amount of health to waste, this fight is an almost guaranteed loss.

What else did you expect from a boss that:
Attacks twice per turn, with no need to approach you?
-Curses you twice per turn?
-Has two invincible buddies to block your shots?
-Summons more enemies on hit?
-Has a whopping 16 health???

This boss has absolutely no right being this hard, for a boss that's literally on the SECOND stage. It's harder than the damn final boss, for pete's sake! Who thought this was a good idea?

If see this boss as Bumbo the Lost, just don't bother. Unless you're absurdly overpowered to the point of being nigh invincible, this fight is impossible as Lost. Just reset.

I'd say wait for an update, but that's probably going to take a year or so to happen. Just pray to the RNG gods that you either don't get this boss, or find any way to skip the boss. That's my genuine advice.