Oh a quick little strategy on how to kill these things. Basically they have two forms. One is when their in their shell and one when their out of it. Inside their shell they recover hp @ insane speed, and out of their shell they act offensively but are most vulnerable. The moment you attack em when their outside they will quickly retreat back into their shell, poison you with very strong poison and start recovering hp. Btw their shell makes ur normal attacks almost nonexistent, including magic and Spirits Within. So how do you beat em. Well the trick is when their in their shell they can't move. So you simply gravity em or run back and when they see that your not attacking and running away they will come out and run towards you. Instantly you cast your strongest spell and it does full dmg. They instantly retreat back inside and u can move back somemore and repeat. It would be an easy mob to manaburn @ lower lvls. You don't even need a tank for em at all