She collected dead Ghosts and tampered with them. We are aware of two sets of criteria. The devotion/sacrifice bit the speaker gave us and the “chosen” person or type of person a Ghost looks for. Remove the “chosen” aspect and all you have left is a vague set of criteria that good and bad people can meet. The location is her throneworld. We are unsure of her manipulation of the Ghost can carry over outside of her throneworld. Technically, it’s wise of her to hide there. She controls the place and without the Worm Pact, she should be able to die in there and still revive.