Oh, I'm sure the letter is interesting, but the question is whether you will actually set up wards and have a supply of holy water on hand before activating the scroll. Though the observation that the existence of the Faerie Queen changes things is a fair point :-)

I don't know if the scenario is all that exciting, it's a pretty standard trope, a bit tarted-up. If you want to grab it and run with it, be my guest.