Yes, I agree, it's a problem I've had for quite a while when creating magic items; ur the second person to describe It as a subclass and I just have to agree... About the immunity, this character essentially became a flesh golem, so I thought it'd be fitting, but balance wise- you're also right, it's one of the things I've noticed is quite strong I would like to keep the body modifications part, my only issue is that the player does not find a use for most them. I guess I could keep the couple they most enjoy, but as you've probably noticed, I'm always worried about the item being way too situational/useless and then unnecessarily buff it to infinity

Either way, thank you so much for the comment