I played it again, and I couldn't manage to wedge myself behind it from the left side (enemies got to me too), I'm curious to see your experience with it haha. But I did also notice if you spam shots from the side and don't pay attention you kinda just melt the boss. I'll probably make the miniboss spawn in way faster once it hits the threshold, maybe use the conveyor belt at the beginning of the room too (surround the player with enemies) and give the boss more HP, or make the normal enemies spawn in faster too.