It's performed using a mana lobe... though I have reason to believe that humans in this place lack such a thing. That being said, it's difficult to explain. Humans in my world have a direct link to spirits and it's dependant on how well-defined their mana lobe in their brain is. I've been told that mine is very well-developed.

[Told by a talking doll.]

[She ponders her words.] It comes rather easy to me, so that must be true. [Also, she's kinda Maxwell, so spirits are a cake-walk.]