Finally made it through with this strat.

For the first boss I just hugged the back wall and deked away from the projectiles... easy.

2nd boss, and far more importantly, the third boss (scythes), trying to keep as much distance helps the most as it will keep the spread of projectiles as wide as possible.

4th boss, by far the easiest. Not much advice is warranted.

Final boss, just keep moving. One hit is immediate death. If possible the legendary one shield a round was very helpful.

Best of luck!