As you’ll notice immediately, the boss is a big beating heart-esque monster on a cross. It shoots blood at you every few seconds, but the good news is that it can’t hit you while you’re moving. If you dodge when you hear this attack’s audio cue (press square/X while aiming) you won’t take any damage if you time it right either. Your first course of action is to get a feel for the area. There are three consoles wrapped with tendrils, as well as supplies. These supplies include a medkit and nails. You technically only need 15 nails to beat the boss, so, as long as you’ve made it this far, you can’t get stuck as long as you know what you’re doing.
The basic gist of the fight is that you have to use all three consoles to get through this section. To start with, find a console and then walk to a part of the walkway that’s close to the boss, remembering to move out of the way when you need to. Shoot it with five nails (or you can use the shotgun if you’d prefer. There are shells for that in this room too.) Once you do, the tendrils on the consoles will come alive. Simply walk up to them and damage them until they’re out of the way. The boss can still hit you while you’re doing this, of course.
A real bleeding heart
You can use whatever you like to hurt the tendril. The crowbar takes it out in about six hits, so you might want to use the electric lance, which just needs a single charge to put them down. Once they’re out of the way, all you have to do is interact with the console. This will show you three spinning wheels with openings in them. This is the tricky part. You want to hit the button on the console while one of the openings is right next to the rod that extends when you press the button.
You need to time this carefully and it might take you a bit of practice to actually get it down. If you’re slightly off, you’ll miss and the tendril will wrap itself around the console again, requiring you to repeat the same steps to get another crack at it. You’ll have to get this right three times in a row to successfully clear each of these. Plus, there are three of them. If you’re having trouble with this part, you can feasibly run out of supplies, but you hopefully won’t have nearly that much issue. Once you successfully activate the third console, a cutscene will play and the final boss of Tormented Souls will die horribly. Huzzah.