None of those told me about this in the first place!

You're not a Maia, so they wouldn't work on you! Or maybe the Elves who remembered what the last war was like didn't come to fight this one, sensibly so, and somehow in Valinor the knowledge of how to keep Maiar out with your walls didn't get passed down. Or perhaps Melkor spread misinformation about it, actually, that's a thing he'd do.

So you don't know the answers to my questions?

I've never built such a wall, never played around with it too much, all I know is what the wild Elves had back beside Cuivienen. It was enough to warn them so they could flee, it was the first magic they learned. Perhaps someone kindhearted told them. They were fucked enough as it was and it could have been even worse.

What do you want to test walls for me?

He hasn't sent me any in a while, but if he sends me unarmed orcs and they go home when told I will tell them to go home.

Then I'd be happy to pop by and test your walls. When?

Well, one of the tests I want to make is whether I can just wallpaper the place in the symbol and have that work or if you can just walk through it by contesting the illusion and not the symbol. We could try that here.

Hit me.

So Loki makes a wall of the symbol, patterned prettily in midair.

She walks through it. Damn. Nah, don't even have to contest the illusion. I think the engraving-in-brick thing must be doing some of the magical work.

Okay... Loki breathes ice into her hands, winds up with something vaguely bricky, etches the symbol into that to see if it spontaneously melts or anything.

It doesn't spontaneously melt. I could contest it by melting the ice instead of by contesting the symbol, though, betcha.

Be my guest. Loki places the ice brick.

She focuses, and starts melting a thin line to connect parts of the symbol. I'd be incovenienced by a thousand of those, but someone with heat as an ability wouldn't especially.

All right, so it wouldn't help if a Balrog comes to call. Loki grabs a rock, turns Lævateinn into something etchy, etches.

That's the version I'm familiar with. She goes bat, tries to flutter over it; the symbol glows and the bat flaps in midair and she concentrates for several seconds before it stops glowing and the bat flutters forwards and immediately back into a woman.

Is the symbol used up permanently now or would you have to do that again to cross again?

Nah, I'd have to keep doing it. I could try eroding away the stone like I did the ice, in which case it's permanently done with, but stone takes way longer than ice to erode.

Loki etches a second instance.

They both glow when she tries crossing. They take longer, but not twice as long. Mind, another thing I could do and am not doing is just throw the stone around, or open up a crack in the ground and swallow it. This is excellent for making sure nothing gets through without you knowing, and for slowing things down. It's not very good for making sure nothing gets through period.

Yeah. Pity I can't just do the illusion cheat, I love being able to cheat at things. If it was underground it wouldn't work?

You can definitely build a wall where the bottom layer of bricks are inscribed and are underground. If they were underground and covered by dirt I'm not sure. I don't know how incarnates do magic, really.

Loki looks for some dirt to bury her brick under.