...I don't think she had a crush on me. And that's - well, partial solution, but the most important part.
If he wants to stop being so fucking evil then it's Valar-in-general who get to lose faster and harder because I'm on hand. Maybe he'd go for it. But if he wants to win and he wants to win under the banner of Being Really Really Evil then it's not gonna work out.
Does inaudibility counter it or does it work the same way my shadow catcher works?
Nah, then you'd need someone to keep singing it. She gestures at the ground and it resolves itself into a brick; she draws some symbol on the brick with her fingernail, which briefly glows red-hot. Boom. A Power has to contest it to get past it, and contesting every brick in a wall takes forever, more than long enough for the little guys to run.
Loki takes an illusion copy. So, how tall does a wall have to be to work at all?
Does anything need to happen besides this symbol being in the wall? Does it have to be engraved? Does anything besides engraving have to happen? Is there anything to be gained from multiple symbols per brick?