Once in the sphere, you will need to find the heart of a demon to power the sphere again. The problem is that can't find a demon anywhere in the sphere ..... (*ping* Unless of course it is OUTSIDE the sphere, which I didn't check since it took off as soon as I entered.) Oke, question : is the demon IN the sphere, or should I just get outside ? anyone ?

Hehe, yep...you did just answer your own question

What arachnia meant was, that it is indeed right outside the sphere have fun

Just for clarification,
you need to go back out the door you originally entered the sphere by. I didn't do this to start with and only found it by accident after much frustration.