Uh...to tell you the truth the only missions I've had so far is "Defeat this really strong monster." And the second time I didn't even defeat it someone else did.

OK so, I'm not the best person to explain it but basically, you know about souls right? Humans believe in souls where I come from.

Basically your soul is in your gem. And your body is just something the gem creates.

So if you get hurt too badly, your body goes POOF and you retreat inside your gem to heal.

As long as you don't crack or smash your gem you'll just keep coming back.