Furi

You will get this trophy after defeating the sixth boss. The Song is definitely one of the hardest bosses in the game and has some very difficult attacks. You will be doing a lot of dodging during the early phases of the fight. There will be no parrying, which is a problem for your health. You will need to focus on getting quick shots in and dodging. Her attacks will mainly consist of charge, electric, and the massive blue beam you saw against The Strap. Keep dodging and try to get as many hits in as you can. After you hit her enough she will go to the bottom of the arena and surround you with orbs. You will have to dodge the electric things being shot at you, and whilst you're doing this get as many charged shots in as you can. This will decrease her health rapidly.

The next phase is pretty much the same as the first but when she is about to charge you, make sure you have a charged shot aiming right at her. Once she gets close enough, shoot her. This will stop her from charging you and takes a chunk of her health off at the same time.

Later on in the fight she will bring up more panels making the arena bigger, you will have the opportunity to parry so make use of that. After parrying make sure to get those quick attacks in, she will have some different attacks now but most of them will involve dodging.

In the last phase you are required to eliminate all of her small electric towers on each side of the arena, you will need to dodge a lot of orbs as well so watch out for that. Once they are all destroyed, all you have to do now is hit her with and then the fight is over. Take your time while approaching her because her attacks will still be in action.

Take a look at this video if you have problems:

Credits go to TheSeraphim17 for making the video.