The background fog, it turns out, sprang into existence - well, achieved its current density over the course of a few degrees - when someone, presumably Matilda, had just begun spewing enormous amounts of ialdae all over the bottom of the world opposite Paraasilan. But its current age-colour would suggest it's younger than that, so apparently it is also a mix.

"Huh. So ialdae sometimes also teleports to destinations. It didn't travel from opposite Paraasilan to become a fog in Gibryel at its normal rate, that much is clear..."

"I wonder why the background stuff behaves so differently?"

"Good question. And we still don't know whether ialdae teleporting itself around is lossy or not - does the background fog mean there was more than this potentiated but then it got expended spreading itself around?"

"I'm not sure. I'm also not sure how... big the background fog is. It's the same everywhere on the map, but the map is only as big as this planet."

"Yeah." Kaylo makes a separate illusion, this one of the moon.

"Yeah. And even farther away is -" He makes a sun illusion.

"It's not necessarily non-lossy, because we don't know where the initial burst came from. And just to be really sure, here's Avirber 6, one of the farthest other planets identified -" Kaylo makes an illusion of it. It's an octagon.

"Yeah. This is more than you spray around just by existing. Did the world catch ialdae?"

"Maybe it did. That would sort of explain it."

"And prompts a heck of a lot more questions than it answers. Can the world use the ialdae it has, and if so, under what circumstances might it do that? It doesn't seem to be holding onto it very hard, we can pick it up - can people take ialdae out of person ialders like that? Why does ialdae sometimes travel if it can move instantly? What would happen if we left these wards here for a century and they just kept eating apparently arbitrary amounts of background magic that entire time, would the structure of the spell hold or would something else happen?"

"If they're not picking up background fog, and they're only getting power from spills, we need to know how fast they're doing it and from how far away so we know if we can expect enough spills - especially since the Linnipese could probably invent their own recyclers if they tried. And whatever they're getting, we need to know how stably they can go on doing it, because that's relevant to any ward renewal schedule."

"Well, if the wards are big enough to cover the whole country, we might be able to make them pick up spills from inside their active area and prevent anyone else from doing that and then people outside Esmaar wouldn't be able to interrupt our supply by building their own recyclers, and there are plenty of ialdic dragons living in Esmaar right now... And if it wasn't getting enough power, anyone with high output could sit inside it somewhere and deliberately spill power at it."

"These wards are little; do you think country-sized ones won't be any more expensive? Also - it's fairly important to be able to put the wards down, or at least make them selectively ignore people. Otherwise they make it difficult to have tourism and go grocery shopping and so on. Need to build that in."

"I expect country-sized ones to be more expensive, but it's hard to tell how much more without trying it, I guess..."

"It's okay if we can only go up to city-sized, that's what the state of the art is, but if that's too expensive to cast we have a problem."

"I guess if we want to test these things, there is conveniently a whole bottom of the world to go around warding bits of."

"There is, it's very handy. Oh, hey, I could probably do ialdae just fine in natural form, easier to mark city sized boundaries from the air..."

"Yes, I don't see a reason why it should matter what shape you're in for ialdae's purposes. I guess wizardry has those gestures that are probably hard to do without hands."

"Yeah. We could probably adapt it for claws - there's separate gestures for fey and merfolk, and leonines manage the standard terrestrial all right with practice - but basically if I want to cast I use human form."