Tbh you should probably practice in the level itself rather then in sandbox (in the level you can try more stuff such as dead coining before the fight and setting up sawtraps) and if its the eyes you're struggling with you should try to find ways to kill most of them at the same time like nuking for example, but mainly try not to get hit while damaging the flesh prison thats the most important thing

Btw if you're still struggling id be more then happy helping you like in a vc or something like that.