The hardest part to any Soulsborne game is figuring out how to overcome a boss. Mortal Shell approaches them with a bit more ease, though this is a fight that is less about equipment and positioning and more about tactic and skill. Since this can be very difficult for people, we wanted to make it easier by explaining how to defeat every boss.
General Information
Since Mortal Shell is a non-linear game, one where you might lack certain resources before any given boss, every boss guide uses the hollowed sword that you start with. Make no mistake, this weapon is extremely powerful and well worth maxing out.
If you are having issues that this guide does not help you overcome, I strongly suggest going back to the starting base and purchase as many rats as you can. These are extremely valuable in regards to healing and can make any boss, regardless of skill, easy.
Beyond that, remember that any fight is doable, provided you don’t get trigger happy. More mistakes stemmed from rushing things than anything else.
Finally, every one of the main bosses besides the first and last have a second form, so keep that in mind.
How to Defeat Crucix, The Twiceborn
Unlike the other bosses, Crucix is an extremely aggressive boss that is fairly slow. As a result, you can actually overwhelm him by being, well, more aggressive.
For the first phase, you really want to be as close to Crucix as possible. Any range will cause him to shoot at you and that is honestly the easiest way to take damage. Instead, you want to move forward, use a basic heavy attack and go into a light combo. Ideally you’ll get two or three hits in before you have to harden. Immediately after being hit, jump back and maintain a small distance until you can harden again, followed by repeating.
During the second phase you kill the archer, meaning you can maintain as much range as you want. As a result, there are basically two ways to handle Crucix. Either you can maintain a lot of range, wait for him to jump at you, harden and then punish or maintain the same basic tactic. It can be a little harder given how aggressive he is, so you might want to opt for just pot shots with the heavy attack poke but he should be pretty easy as he has a much simpler move set.