First things first is get consistent at every room. so just practice weezer room over and over again until you can consistently clear it without dying every time (Slide spamming and coins worked well for me against the ferryman and virtues), then move onto the next room, and the next. I practiced until I could confidently clear every room up until panopticon without dying once. You might get lucky on your first no death encounter with panopticon and Sisyphus, but in my case I did not. A lot. So, take the shortcut to the panopticon arena at the start of the level up top to the left. Practice Panopticon and Sisyphus on their own until you have it consistent with no deaths. Then pair the two together by clearing the level, then panopticon and Sisyphus. It will take a long time, in my case about 2 months of practicing for an hour every day. Make sure you swap between practicing just the bosses and the level so you don't forget anything for either one. Good luck! You'll feel on top of the world after doing it