[quote=@Realmatic]
<Snipped quote by Etcetera>

Do the runes that cause things remain in the air? Like the one for the big wall?
[/quote]

Yes, but they can fade over time; it depends on the medium. The one for the wall earlier wasn't caused by a drawn rune; PD has tons of them pre-drawn and another set up that responds to voice control to activate the correct one accordingly.