Shane naturally did not know that before he even made contact, Magie had already secretly ventured into Elf Country and met with Merica.
This was not only to investigate Shane and his companions but also to set up some contingencies for when she would confront Shane in the future.
Thus, Magie had used spirit magic at that time to control Merica and made her reveal everything she knew.
Because of this, Magie was so knowledgeable about Shane's affairs and clearly understood the details about everyone around him.
Afterward, Magie planted some of her spiritual power within Merica's body, intending to manipulate her again when necessary, turning Merica into her own puppet to do her bidding.
No matter how you put it, confronting someone backed by Demon Spirits and an Evil God, Magie, despite her nasty character, still made the necessary preparations.
